Knowledge Type: Clinical Articles

Introduction

By June 15^th 2020, 7,997,084 people were infected with SARS-CoV-2, and 435,662 had died. The world economic loss is estimated to be at least $1 trillion. In response, multiple vaccine trials are underway, but none are expected to be out of phase 3 trials until mid-2021.

This delay has necessitated the reassignment of several drugs from their original treatment purpose so as to rebuild the antiviral armamentarium. One of these redirected drugs is hydroxychloroquine (HCQ), currently approved in Australia for discoid and systemic lupus erythematous, rheumatoid arthritis and the suppression and treatment of malaria.

Early trials with HCQ were equivocal at best, forcing clinicians to balance the possibility of clinical benefit against the cardiotoxic effects in vulnerable patients with multiple comorbidities.

In mid-May 2020, three significant papers were released which add more certainty to the use of HCQ, or its precursor, chloroquine (CQ) in COVID-19 (C-19) patients.

On May 22^nd 2020, in The Lancet, Mehra and co-workers reported the results of an international, observational registry analysis involving the use of chloroquine or hydroxychloroquine with or without a macrolide (azithromycin or clarithromycin) between 20 December 2019 and 14 April 2020, in COVID-19 patients across 671 hospitals. There were 96,032 patients in the study. Of these, 1868 received chloroquine only, 3783 received chloroquine with a macrolide, 3016 received hydroxychloroquine only, and 6221 received hydroxychloroquine with a macrolide. There were 81,144 patients in the control group.

The mean daily doses of the various drug regimens were: chloroquine alone – 765mg; hydroxychloroquine alone – 596mg, chloroquine with a macrolide – 790mg; and hydroxychloroquine with a macrolide, 597mg.

After controlling for confounders, the researchers reported that the mortality in the control group was 9·3%, in the hydroxychloroquine group it was 18·0%, in the hydroxychloroquine plus macrolide group it was 23·8%, in the chloroquine alone group it was 16·4%, and in the chloroquine with a macrolide cohort is was 22·2%.  Each treatment modality was independently associated with an increased risk of in-hospital mortality.

Commenting on the Lancet study, Dr Josh Davis of the Doherty Institute and principal investigator of the ASCOT (hydroxychloroquine) study planned by the Institute noted that patients in the Lancet paper who received HCQ  “ … had a higher risk of death at baseline than those who didn’t. They were sicker and they had more comorbidities. That alone could potentially explain the higher risk of death. The only way of knowing whether that’s true or not is to do a randomised trial.”

This concern is well-founded because the co-administration of CQ/HCQ and a macrolide is known to cause an increased corrected QT interval. A prolonged QT interval (the time required for the ventricles to depolarise and repolarise) can precipitate ventricular arrhythmias such as torsades de pointes, which can spiral into ventricular fibrillation.

The Subsequent Controversy

On 23 May 2020, one day after publication of the Mehra paper, the World Health Organization (WHO) paused patient recruitment into the hydroxychloroquine arm of the SOLIDARITY trial, citing safety issues with HCQ that were highlighted by Mehra et al.

The SOLIDARITY study is an adaptive, randomised, open-label, controlled clinical trial, in collaboration with countries around the world through the World Health Organization.

Subjects will be randomised to receive either standard-of-care products or the study medication plus standard of care, while being hospitalised for COVID-19.

Participants will be randomised to one of the following groups:

1. Lopinavir/ritonavir 400mg/100mg orally twice daily for 14 day plus local standard care, OR
2. Hydroxychloroquine 800mg twice daily for 1 day then 400mg twice daily for 10 days plus local standard care, OR
3. Remdesivir 200mg IV on day 1, followed by 100mg IV daily infusion for 9 days plus local standard care, OR
4.  Lopinavir + ritonavir (orally twice daily for 14 days) plus interferon-beta (daily injection for 6 days). OR only
5. Local standard support care.

“The patients will be followed up for the entire length of their hospital stay. Death from any cause will be recorded and this will be the main result used to determine whether a drug is effective. Length of hospital stay and time to first receiving ventilation (or intensive care) will also be recorded and used to determine the drug’s effectiveness.”

By 28 May 2020, there was a swift international response to the Lancet study, with 201 scientists co-signing an open letter to the study authors and Mr Richard Horton, Editor of The Lancet. They cited ten concerns including the non-release of data source codes, no ethics committee review, mean daily doses of hydroxychloroquine that are 100mg higher than FDA (US Food and Drug Administration) recommendations, inadequate allowance for confounders, and more technically, “the tight 95% confidence intervals reported for the hazard ratios appear inconsistent with the data. For instance, for the Australian data this would imply about double the numbers of recorded deaths as were reported in the paper.”  The authors also denied a request for information on the contributing study centres.

On 29 May, the authors published a correction pertaining to the countries of origin for some of the data. They noted: “the numbers of participants from Asia and Australia should have been 8101 (8·4%) and 63 (0·1%), respectively. One hospital self-designated as belonging to the Australasia continental designation should have been assigned to the Asian continental designation…  The unadjusted raw summary data are now included. There have been no changes to the findings of the paper. These corrections have been made to the online version as of May 29, 2020, and will be made to the printed version.”

On 3 June 2020, the Editor of The Lancet issued an Expression of Concern letter, due to serious questions pertaining to the integrity of the data supplied to the researchers by Surgisphere, a company started by Dr Sapan Desai, one of the authors of the Mehra paper.

On the same day the Director-General of WHO announced that on the basis of the available mortality data, the Executive Group of the Solidarity Trial had agreed to the continuation of all arms of the Solidarity Trial, including the hydroxychloroquine arm, as there was “no reasons to modify the trial protocol”.

Finally, on 4 June 2020, the Mehra paper was withdrawn by three of the authors. In the notification published by The Lancet it was stated the authors “… were unable to complete an independent audit of the data underpinning their analysis. As a result, they have concluded that they “can no longer vouch for the veracity of the primary data sources.” The Lancet takes issues of scientific integrity extremely seriously, and there are many outstanding questions about Surgisphere and the data that were allegedly included in this study.”

In a further twist to the SOLIDARITY trial, on June 17^th the WHO announced that they were reversing the decision to reinstall the HCQ arm of the trial, and were cancelling further enrolment of patients in this arm.

The decision was predicated “on evidence from the Solidarity trial, UK’s Recovery trial and a Cochrane review of other evidence on hydroxychloroquine.

Data from Solidarity (including the French Discovery trial data) and the recently announced results from the UK’s Recovery trial both showed that hydroxychloroquine does not result in the reduction of mortality of hospitalised COVID-19 patients, when compared with standard of care.”

Patients already taking HCQ will either complete their course or stop at the discretion of the supervising physician.

“This decision applies only to the conduct of the Solidarity trial and does not apply to the use or evaluation of hydroxychloroquine in pre or post-exposure prophylaxis in patients exposed to COVID-19.”

Mahévas research

On May 22^nd, 2020, Mahévas and others (BMJ)  published the results of a comparative observational study of patients (n = 181) hospitalised between March 12-31, 2020. The study cohort was aged 18-80 years with documented SARS-CoV-2 pneumonia who required oxygen but not intensive care (IC).

The treatment group (n=84) received HCQ 600mg per day within 48 hours of admission, another eight patients received HCQ more than 48 after admission, and the control group (n = 89) did not receive HCQ.  The authors concluded that the use of HCQ in COVID-19 patients admitted to hospital requiring oxygen was not supported by the evidence.

Brian J Lipworth, Professor of Pulmonology (Scottish Centre for Respiratory Research, Ninewells Hospital and Medical School) noted that 85% of patients in this study who were given HCQ had evidence of the cytokine storm because their C-reactive protein (CRP) levels were greater than 40mg/L on admission. A CRP higher than 42mg/l on admission is predictive of a poor outcome.

Hence, there was no clinical merit in treating 85% of these patients with HCQ – they were already in the storm phase. The putative mechanisms of action of HCQ-only therapy include interference with viral binding to the angiotensin-converting enzyme II (ACE2) pulmonary receptor, thus reducing viral-cell membrane fusion, and increasing intracellular pH, thereby reducing viral replication.

The presence of the cytokine storm of interleukin-6 (IL-6) means that HCQ use is clinically too late. Only drugs such as tocilizumab, an IL-6 receptor blocker, have clinical justification at this point in the disease progress.

Carlucci research

The third paper in May 2020 was by Carlucci and co-workers who conducted an observational study on patients hospitalised at four New York hospitals between March 2^nd 2020 and April 5^th 2020, using the triple therapy of hydroxychloroquine (HCQ), azithromycin (AZM) and zinc sulfate (Zn) compared to HCQ plus AZM only use (pre-print, not yet peer-reviewed).

In the triple therapy arm, 411 patients had received hydroxychloroquine 400mg as a loading dose, then 200mg twice a day for five days, zinc sulfate 220mg (containing 50mg elemental zinc) twice daily and azithromycin 500mg daily.

In the comparator arm, 521 patients took HCQ plus AZM only, at the same treatment level. All patients received usual supportive care.

Univariate analyses revealed that zinc sulfate increased the frequency of discharges home, and decreased ventilation need, ICU admissions, mortality or transfer to hospice for patients who were never admitted to the ICU.

After adjusting for the time at which zinc sulfate was added, there remained a significant increased frequency of being discharged home, a reduction in mortality and a reduction in hospice transfer.

There are several caveats to note. First, this study is still in the pre-peer review stage. Second, it was, like those of Mahevas and Mehra, a retrospective, observational study, leading to many potential confounders influencing the results. Carlucci noted the following:

1. There was uncertainty as to when each medication was given (as distinct from when it was charted);
2. The time when each group commenced their therapy may have differed;
3. They were uncertain if the observed added benefit of zinc sulfate to hydroxychloroquine and azithromycin on mortality would have been seen in patients who took zinc sulfate alone or in combination with just one of those medications;
4. This study should not be used to guide clinical practice; and
5. The point in clinical disease status at which patients received those medications could have differed between our two groups.

The difference in the S and R forms of hydroxychloroquine

In a pre-print paper (not yet certified by peer review), Guanguan Li and co-workers have reported that in all clinical trials, chloroquine diphosphate or hydroxychloroquine sulfate have invariably been used. These formulae are a 50/50 racemic mixture of the R- and S- forms. However, their laboratory tests have shown that there are stereoselective differences in the respective potencies of the R- and S-enantiomer for both chloroquine and hydroxychloroquine against live SARS-CoV-2.

“S-chloroquine (S-CQ) and S-hydroxychloroquine (S-HCQ) were found to be 27% and 60% more active against SARS-CoV-2, as compared to R-CQ and R-HCQ, respectively.”

Added to this is the knowledge that “S-chloroquine seems to be less toxic than the R-chloroquine.” By extension at least, it is reasonable to conclude that S-hydroxychloroquine is less toxic than R-hydroxychloroquine, though clinical trials would need to verify this assumption.

Zinc, immune function and antiviral properties

This study poses an interesting clinical question – why was there a benefit in the zinc arm of the review?

Age is a significant factor contributing to C-19 mortality. A Chinese study (n =72,314) reported that whilst the overall mortality rate was 2.3%, the rate increased proportionally with age reaching 8% in those aged 70–79 years and 14.8% in those ≥80 years old.

One possible contributing factor to the age-related death rate is evidence showing a decline in immune function with advancing years, known as immunosenescence, with studies suggesting an impaired T-cell function against pathogens. Zinc is a contributor to functional immune capacity, with a deficiency causing a rapid reduction in innate and acquired immunity. Hence zinc is considered an essential antiviral micronutrient.

The evidence points to zinc’s antagonistic role in viral transcription. Replication of all positive-strand RNA viruses, such as SARS-CoV and SARS-CoV-2, require membrane-embedded RNA-dependent RNA polymerase (RdRp). This enzyme is at the core of the viral RNA replication machinery.  RdRp catalyses the replication of RNA from RNA templates.

Hence the importance of research by te Velthuis and co-workers who have shown that zinc inhibited SARS-CoV RdRp elongation. When compared to alternate metal ions such as cobalt or calcium, zinc was the most effective inhibitor. Zinc caused a 3-4 fold reduction RNA binding to the assay template.

Figure 1. Increasing zinc (Zn²⁺) concentration causes a decreasing level of RNA1, due to declining RdRp activity (from te Velthuis et al.)

However, it is clinically challenging to achieve an antiviral intracellular concentration of zinc because it is bound to metallothioneins.

The answer to increasing the intracellular zinc levels is to use an ionophore, a chemical species that carries ions across a cell membrane before releasing the species into the cytoplasm. Te Velthuis achieved RdRp inhibitory levels of zinc by using pyrithione (PT) as the ionophore – Carlucci used hydroxychloroquine.

It is important to note that te Velthuis tested zinc against SARS-CoV, whereas Carlucci tested it against SARS-CoV-2, another member of the coronavirus family. Because the amino acid sequence identity between SARS-CoV and SARS-CoV-2 S-proteins is 76.47%, it is clear that these two viruses are genetically closely related, hence the efficacy of zinc against both species. Reinforcing their commonality is that their access into a host cell uses the same cell surface receptor – ACE2.

Conclusions

Zinc is a vital immune-related micronutrient and possesses dual antiviral activity. It enhances the activity of both the innate and acquired immune system and impedes RNA-dependent RNA polymerase (RdRp). HCQ also has a putative duality of antiviral action. It interferes with the ACE2 receptor, potentially impeding ACE2/SARS-CoV-2 binding, and it has been shown to increase the endosomal pH, which may impair SARS-CoV-2 early-stage viral replication.

Triple therapy for five days of HCQ 400mg immediately then 200mg twice daily, AZM 500mg daily and zinc sulfate 220mg – containing 50mg elemental zinc – twice daily has shown clinical benefit in non-ICU bound patients.  These results are yet to be confirmed by peer review.

Finally, the use of HCQ in patients with a high CRP is without clinical justification.

Introduction

On 31 December 2019, China reported a cluster of cases of pneumonia in people from Wuhan, Hubei Province. The responsible pathogen was a novel coronavirus, named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is the cause of COVID-19, a disease which can result in death associated with acute respiratory distress syndrome (ARDS), usually secondary to pneumonia.

By 16 May 2020, there were 4,555,803 people infected worldwide, with 304,201 deaths. The estimated damage to the world economy for 2020 is $1 trillion.  At least $5 trillion has been allocated by first world countries as part of an economic rescue package for their businesses and workers.

There are intensive international efforts to discover a vaccine to SARS-CoV-19. A commercially available vaccine may not be through phase 3 trials until mid-2021.

Against the background of this viral pandemic, currently available medications are under investigation as treatment options for COVID-19. One of these is tocilizumab (TCZ).

Tocilizumab

Tocilizumab (Actemra^®) is indicated for rheumatoid arthritis (with methotrexate, if possible), juvenile idiopathic arthritis (systemic or polyarticular – with methotrexate, if possible), giant cell arteritis (GCA), with adjunct corticosteroid treatment, and in cytokine release syndrome induced by chimeric antigen receptor T cell (CAR-T) therapy. It is available as 80 mg in 4 mL, 200 mg in 10 mL and 400 mg in 20 mL.

Tocilizumab is a humanised monoclonal antibody (IgG). It binds to the interleukin-6 (IL-6) receptors throughout the body leading to rapid reductions in erythrocyte sedimentation rate (ESR) and concentrations of C-reactive protein (CRP).  Tocilizumab may increase the activity of hepatic enzyme 1A2, 2C9, 2C19 and 3A4, thereby potentially affecting the metabolism of other drugs.

In the AMBITION study, most adverse reactions were mild or moderate, with less than 3.8% of patients experiencing severe adverse reactions. Skin infections were the most common, but less than the rate seen in patients taking methotrexate. Liver function tests were elevated, but without signs or symptoms of hepatitis or hepatic dysfunction. Mouth ulceration and gastritis have also been reported, and some patients have suffered perforation of the gut, mainly secondary to diverticulitis.

Lung histology

A brief review of lung histology is beneficial to the understanding of the link between IL-6 and SARS- CoV-2’s lethality.

The alveolar epithelium is composed of three types of cells:

• Type I cells which comprise 90% of the alveolar surface area,
• Type II cells which are approximately 10% of the area, and contain the ACE2 receptor
• Macrophages

Type 1 cells are responsible for gas exchange, whilst type II cells produce a surfactant which lowers the cell surface tension at the air-liquid (inhaled water) interface, thereby preventing the alveoli from collapsing together. Type II cells also remove excess alveolar fluid through intracellular transport and contain the angiotensin-converting enzyme 2 (ACE2) receptor.

Macrophages are the most numerous immune cells present in the lung environment under homeostatic conditions. They are integral to the innate defence of the airways. They exhibit a malleability of function which covers the maintenance of pulmonary homeostasis, microbial clearance, removal of cellular debris, immune monitoring, responses to infection and the resolution of inflammation.

The role of interleukin 6 (IL-6)

Inflammation is a core initiator of the innate immune system and is the body’s first line of defence against infection or injury. Inflammation also activates the adaptive (or acquired) immune system.

Interleukin-6 is classified as a pro-inflammatory cytokine and is produced predominantly by activated macrophages, but also T cells, endothelial cells, fibroblasts and hepatocytes. IL-6 exhibits a duality of functionality – it also responds to neutrophils and monocytes/macrophages (part of the innate immune system). This duality can cause amplification of inflammation and a switch from an acute to a chronic inflammatory state.

IL-6 is considered one of the most important cytokines released during a viral infection and aids host defence by the up-regulation of acute phase responses such as C-reactive protein (CRP), serum amyloid A (SAA), fibrinogen, and haptoglobin, and decreases the levels of fibronectin, albumin and transferrin. IL-6 has a stimulatory effect on T- and B-cells (part of the adaptive/acquired immune system). In particular, “IL-6 promotes specific differentiation of naïve CD4+ T cells, thus performing an important function in linking the innate and acquired immune response.”

The production of IL-6 is tightly controlled, and cytokine down-regulation is vital because dysregulated production of IL-6 has a deleterious effect on both host autoimmunity and inflammation. For example, elevated IL-6 levels reduce zinc levels, and can induce autoantibody production, thrombocytosis and hypergammaglobulinaemia. Also, excessive levels of SAA cause amyloid fibril deposits, resulting in gradual multi-organ deterioration, whilst increased hepcidin levels reduce serum iron levels, causing hypoferremia and anaemia.

The down-regulation of the IL-6 mediated inflammatory response is effected by IL-10, an anti-inflammatory cytokine, as well as transforming growth factor β (TGF-β). The reduction in IL-6 activity is necessary so as to prevent the “cytokine storm” – a lethal state of systemic inflammation.

SARS-CoV-2, immune response and the cytokine storm

When SARS CoV-2, an enveloped, single-stranded, positive-sense RNA virus is inhaled, it gains entry into the host cell in a two-stage process.

First, the viral spike (S) protein binds to the ACE-2 receptor, located on type-II cells. This facilitates viral attachment. The S protein is then further primed for fusion and entry into the host cell by the protease, TMPRSS2.

As a result of this binding and host invasion by SARS-CoV-2, both the innate and the adaptive immune systems are activated, with the consequent release of numerous types of cytokines including IL-6. This constitutes a functional immune response.

However, in severe COVID-19 patients, the immune response becomes dysregulated, with a pathological effect on both inflammation and autoimmunity. In particular, there are elevated levels of IL-6 which contributes to the cytokine storm, an immune system over-reaction.

IL-6 levels in COVID-19 patients have been reported to exceed 627.1pg/mL before TCZ therapy. The normal level is 5pg/mL or less.

Aside from elevated IL-6 levels, severe COVID-19 patients also have lower levels of beneficial CD4⁺ and CD8⁺ T cells, both of which are part of the adaptive (or acquired) immune system.

This effect of IL-6 confirms that the cytokine storm diminishes adaptive immunity against SARS-CoV-19 infection, thus making the patient less likely to recover. As Liu, et al. (2020) has noted, “The more serious the disease and the worse the prognosis, the lower were the T cell, CD4+ T cell, and CD8+ T cell counts on admission. Based on these findings, we believe that the CD4+ and CD8+ T cell counts in patients with COVID-19 could reflect disease severity and predict disease prognosis and are therefore good biomarkers of COVID-19 activity.”

In short, IL-6 shifts from acting to protect the host due via a regulated immune system, to becoming a threat to host survival due to a dysregulated immune system.

Mechanism of the cytokine storm

The replication and release of the virus cause inflammatory host cell death (pyroptosis).  Damage-associated molecular patterns (DAMP) are recognised by alveolar macrophages which start the production of pro-inflammatory cytokines and chemokines including IL-6. The initial action of IL-6 is beneficial to the host as it contributes to the immune response. However, as further monocytes, macrophages and T cells are attracted to the infection site, due to the increasing number of viral particles, there is an augmentation of the inflammation process. A pro-inflammatory cytokine “feedback loop” is created.

The dysregulated consequences associated with the increase in IL-6 include enhanced vascular endothelial permeability, resulting in increased levels of neutrophils in the lungs. Neutrophil entry into the lungs is a defining feature of ARDS. Neutrophils cause an increase in capillary permeability, resulting in alveolar oedema and arterial hypoxaemia, further compromising ongoing gas exchange and adding to the onset of ARDS. ARDS mortality corresponds to the degree of neutrophilia in the lung. There is also a diffuse thickening of the alveolar wall, further decreasing gas exchange.

Respiratory failure caused 69.5% of deaths in one Wuhan hospital cohort of 82 patients.

Another consequence of neutrophil-induced capillary permeability is that pro-inflammatory IL-6 can escape into the systemic circulation. The systemic ‘escape’ of supraphysiological levels of IL-6 is implicated in multi-organ damage, including kidney disease, cardiovascular disease including fulminant myocarditis, and hepatic failure. The systemic viral damage occurs because IL-6 receptors are ubiquitous. Foetal tissue studies show IL-6 receptors not only in the lungs but also the eye, heart, liver, spleen, and adrenal, renal and gastrointestinal tissue.

Adding to the consequences of the cytokine storm is clinical evidence from human and animal studies indicating that an “overexpression of IL-6 might be a possible mechanism favouring persistence of some viruses”, perhaps secondary to the reduced levels of CD4⁺ and CD8⁺ T cells noted earlier.

The multi-factorial interplay of immune components, cytokines and SARS-CoV-2 is well represented in Figure 1.

Figure 1: Cytokine storm and T cell lymphopenia is associated with COVID-19 severity (reproduced with permission from Pedersen et al.)

SARS-CoV-2 infection causes COVID-19. Compared with uninfected individuals (left panel), moderate COVID-19 cases exhibit an increase in IL-6 and a decrease in total T lymphocyte counts, particularly CD4+ T cells and CD8+ T cells (middle panel). Severe COVID-19 cases have further increased production of IL-6, IL-2R, IL-10, and TNF-α, while total T lymphocytes, particularly CD4+ T cells and CD8+ T cells, and IFN-γ–expressing CD4+ T cells markedly decrease (right panel). The level of cytokine storm and T cell lymphopenia is associated with pulmonary damage, respiratory distress, and unfavourable outcome. ARDS, acute respiratory distress syndrome; CRP, C-reactive protein; LDH, lactate dehydrogenase.

SARS-CoV2, cardiovascular complications and ACE2 receptors.

Research indicates that there are several prognostic indicators for severe disease and ICU admission in COVID-19 patients. These include being elderly and having underlying comorbidities such as chronic obstructive pulmonary disease (COPD), cardiovascular disease and hypertension. One study has reported that 21% of COVID-19 patients had hypertension. Hypertension is associated with a nearly 2.5-fold significantly increased risk of severe COVID-19 disease and a similar significantly higher risk of mortality. Cardiovascular morbidity – characterised by tachyarrhythmias, elevated troponin, and thromboembolic events – is reported in 20% of hospitalised patients and is strongly allied with mortality risk.

The elucidated explanation for the higher mortality rate in hypertensive patients is due to the destruction of the ACE2 receptors after SARS-Cov2 binding to the type II cells and subsequent cell lysis.

Importantly, ACE2 receptors are also located on the heart, gastrointestinal tract and kidneys at higher levels than are found in the lungs.

The physiological function of ACE2 is to convert angiotensin II to angiotensin 1-7. The ACE2-angiotensin 1-7 axis is a counterbalancing arm to the ACE1-angiotensin II arm of the renin-angiotensin system (RAS).

Angiotensin II can induce vasoconstriction and possesses pro-inflammatory and profibrotic capacities. In contrast, angiotensin 1-7 is antiproliferative, antiapoptotic and has vasodilating actions. It is also cardioprotective in its capacity to be anti-heart failure, antithrombotic, anti-myocardial hypertrophy, antifibrosis, antiarrhythmic and anti-atherogenic.

As can be appreciated, with the destruction of ACE2 receptors on type II cells, the delicate balance between ACE1 and ACE2 can lead to dysregulation of blood pressure and other deleterious cardiovascular sequelae.

The role and interplay between SARS-CoV2, the RAS and higher mortality rates are elegantly portrayed in Figure 2.

Figure 2. The severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2)/severe acute respiratory syndrome coronavirus (SARS‐CoV) infection could possibly influence the balance between angiotensin II (Ang II) and angiotensin 1‐7 (Ang‐[1‐7]) (from Guo et al.)

*indicates finding in hearts; ACE1, angiotensin‐converting enzyme 1; ACE2, angiotensin‐converting enzyme 2; ACEI, angiotensin‐converting enzyme inhibitor; Ang I, angiotensin I; ARB, angiotensin receptor blocker; ARDS, acute respiratory distress syndrome; AT1R, angiotensin II type 1 receptor; dotted line, speculation based on the current evidence; solid line, findings from current evidence; up arrow, promote; down arrow, inhibit.   

SARS-CoV-2 and stroke in COVID-19 patients

On 28 April 2020, the New England Journal of Medicine reported on five COVID-19 patients who presented with large-vessel stroke. A possible explanation may involve virus-induced destruction of the ACE-2 receptor and reduced AT1-7 generation, the production of superoxides causing resultant endothelial damage, and the putative impact of this cascade on the release of von Willebrand factor (vWF) and the link to clot formation and stroke. The release of vWF is also triggered by IL-6.

Kerr (2001) reported that IL-6 promotes coagulation via an increased transcription of Factor VIII as well as causing a 4.5-fold increase in tissue factor mRNA. IL-6 also increases both platelet production and activation, and vWF. Similarly, Chin (2003) has reported that “elevated IL-6 may contribute to the thrombotic and thromboembolic complications in acute heart failure, in a process mediated via increased TF [tissue factor] and vWF.”

Peyvandhi (2011) and Escher (2020) have concluded that vWF plays a pivotal role in primary haemostasis by facilitating platelet adhesion to damaged vascular endothelium and subsequent platelet aggregation. High levels of vWF, in part caused by elevated IL-6 levels, are predictive of endothelial activation, disease outcome and future prothrombotic events.

Trials supporting TCZ in COVID patients

Fu et al. (2020) reported on a trial of TCZ in 21 severe or critical COVID-19 patients with elevated IL-6 levels of greater than 20pg/mL. Patients were receiving standard treatments including lopinavir, methylprednisolone, other supportive treatments and oxygen. To recall, the normal level of IL-6 is 5pg/mL or less.

Patients were given a first dose of TCZ at 4-8mg/kg (recommended 400mg), diluted to 100mL with 0.9% normal saline and infused over one1 hour. For poor responders, the same dose as the first was given 12 hours later. No single dose over 800mg was given.

Twenty of twenty-one patients recovered and were discharged within two weeks, whilst one patient was slower to be discharged.

The researchers concluded that “Tocilizumab treatment is recommended to reduce the mortality of severe COVID-19.”

It is important to note that there may be a transient increase in IL-6 levels lasting a few days after administration of TCZ because the IL-6 receptor is now blocked.

Michot and colleagues (2020), in a journal pre-proof case publication have reported on an immunocompromised patient with renal cell carcinoma, who tested positive for SARS-CoV-2.  A chest computerised tomography (CT) scan revealed bilateral patchy ground glass opacities. Lopinavir-ritonavir (400mg-100mg orally) was commenced on day seven for five days. On day eight, sudden dyspnoea occurred with a saturation drop requiring oxygen at 6L/min, but without artificial ventilation.

The patient was given two doses of TCZ, 8mg/kg IV, eight hours apart. He became rapidly afebrile, with good clinical improvement and was slowly weaning off oxygen. A day 12 chest CT showed partial regression of the pulmonary infiltrates and ground glass appearance. His C-reactive protein (CRP), a surrogate marker for cytokine storm has reduced from 225mg/L to 33mg/L in four days.

The reference range normal for CRP is less than 5mg/L, and a CRP greater than 10mg/L is indicative of an acute infection or inflammation.

Luo et al. (2020) conducted a retrospective study of 15 COVID-19 patients. Two patients were moderately ill, six were seriously ill, and seven were critically ill. Eight patients received TCZ with methylprednisolone (MPS). Five patients received two or more dose of TCZ. Four of the critical patients only received one dose of TCZ 320-600mg plus MPS 40mg -160mg across 3-5 days.

Before TCZ therapy, the CRP level in deceased patients 1,2 and 3 ranged from 175.8mg/L to 257.9mg/L and reduced to 12.8-51mg/L prior to death.

Interestingly patient 6, who survived, had a pre-TCZ CRP of 253.1 mg/L which reduced to 5.0mg/L on day 7.

The pre- and post-TCZ IL-6 levels followed the predicted pattern of an increased level post-TCZ in 14 of the 15 patients. Some post-TCZ levels were dramatic. For example, patient 4’s level increased from 392 pg/mL pre-TCZ to 935.5 pg/mL one day after TCZ but reduced to 396.8 pg/mL on day 4.

Also, the pre-TCZ IL-6 level was not always predictive of outcome. Patients 1, 2 and 3 had pre-TCZ IL-6 levels of 16.4, 32.7 and 73.6pg/mL respectively. At the time of death, the IL6 levels ranged between 2230.0 – 5000.0pg/mL. In comparison, patient 14 had a pre-TCZ IL-6 level of 627.1pg/mL which reduced to 249.0 pg/mL on day 7.

Whilst this study has many weaknesses, including variable doses of variable drugs and low study numbers, the overall conclusion by the authors was that in critically ill patients, or those with a high IL-6 titre, two or three doses would be clinically indicated.

The 29 April 2020 pre-publication information from the CORIMUNO-TOCI French study of 129 COVID-19 patients with medium to severe pneumonia suggest that there was a significant reduction in the proportion of patients who had to be transferred to resuscitation units or who died. Half of the patients received one or two injections of TCZ plus standard care (oxygen, antibiotics and anticoagulants) whilst the other half received only standard care. Follow-up was 14 days. Importantly TCZ was effective in preventing the “inflammatory storm.”

Conclusion

Because there is little expectation of a vaccine to SARS-CoV-2 before 2021, there is a pressing, indeed urgent need for the safe and prudent use of currently available medications. The mechanism of action of tocilizumab theoretically suggests, and early research confirms, that it is a suitable candidate in moderate-severe COVID-19 patients.

Over the past years, there has been emerging evidence suggesting that inflammation plays a key role in ischemia/reperfusion-related injury in patients presenting with ST-elevation myocardial infarction (STEMI). However, little venture out to examine if this is possible in a clinical setting due to the lack of anti-inflammatory agents with favourable cardiovascular safety profiles. Colchicine, typically prescribed for the treatment of gout, displays potent anti-inflammatory properties but also allows for safe use in patients with cardiovascular disease. Recent studies have shown a short course of treatment with colchicine could lead to reduced major adverse cardiovascular events in acute myocardial infarction.

The New England Journal of Medicine conducted a double-blinded study to test if a short course of treatment with colchicine could lead to a reduction in atherosclerosis and its complications. The study titled COLCOT enrolled a total of 4745 patients, of which 2366 patients were assigned to the colchicine group. They received low dose colchicine of 0.5mg once daily. They were followed for a median of 22.6 months. The study concluded that patients assigned to the colchicine group had a significantly lower risk of ischemic cardiovascular events than the placebo group.

The primary end point of this study shows the possible benefit of low dose colchicine in patients with confirmed acute myocardial infarction. However, the COLCOT study also highlighted the increased report in diarrhoea and pneumonia, 9.7% vs 8.9% and 0.9% vs 0.4% respectively. Health professionals should exercise caution when prescribing colchicine and consider the possibility of polypharmacy and adding to the already large amount of medication prescribed post-myocardial infarction.

From 1st June 2020, listings for opioid medicines on the Pharmaceutical Benefits Scheme (PBS) will change. The changes will include the addition of listings for smaller maximum quantities as well as updates to existing restriction criteria and arrangements for increased quantities and repeats. These changes are in response to recommendations from the Pharmaceutical Benefits Advisory Committee (PBAC) and form part of a range of regulatory measures to address the issue of opioid harm in Australia.

The products contained in Table 1 are currently listed on the PBS and have been identified as appropriate for acute pain. The PBAC has recommended the introduction of PBS listings for smaller quantities of these medications with no repeats. Opioids that are currently restricted for use in chronic pain, pain due to cancer, or palliative care are not included in this proposal to reduce pack sizes.

Table 1. Opioid medications considered for reduced pack sizes on the PBS

Drug	Presentation	Current PBS maximum quantity	Proposed PBS maximum quantity
Codeine	Tablet (codeine phosphate 30mg)	20	10
Codeine + paracetamol	Tablet (codeine phosphate 30mg + paracetamol 500mg)	20	10
Hydromorphone	Oral liquid (hydromorphone hydrochloride 1mg/mL)	1 x 200mL	*
	Tablet (hydromorphone hydrochloride 2 mg)	20	10
	Tablet (hydromorphone hydrochloride 4mg)	20	10
	Tablet (hydromorphone hydrochloride 8mg)	20	10
Morphine	Tablet (morphine sulfate 30mg)	20	10
Oxycodone	Capsule (oxycodone hydrochloride 5mg)	20	10
	Tablet (oxycodone hydrochloride 5mg)	20	10
	Capsule (oxycodone hydrochloride 10mg)	20	10
	Oral liquid (oxycodone hydrochloride 1mg/mL)	1 x 250mL	*
Tramadol	Capsule (tramadol hydrochloride 50mg)	20	10

*New PBS listings will not be created for liquid formulations until a smaller pack size is available.

Sponsors of relevant medicines have been given 24 months from January 2020 to register new smaller pack sizes with the Therapeutic Goods Administration (TGA). However, the TGA does not have the authority to compel a sponsor to actually supply smaller pack sizes in Australia.

While prescribers are already able to prescribe less than the maximum quantity for existing PBS items, these new listings are intended to simplify the process prior to smaller packs being available. Long-term opioid therapy will still be available on the PBS for the management of chronic pain. However, larger pack sizes and repeats will require authority approval from 1^st June 2020. Prescribers must ensure that patients meet the relevant criteria when prescribing opioids under the new Restricted Benefit and Authority Required PBS listings.

Details on all new and amended restrictions will be available for review on the PBS website from 1^st June 2020.

Introduction

It is important to distinguish between three commonly used descriptors in connection with the current viral pandemic. These are:

• Coronavirus;
• SARS-CoV-2; and
• COVID-19.

Coronaviruses are a large group of viruses that are the genesis of respiratory infections and can cause mild medical problems such as the common cold through to more serious infections. This group of viruses is so named because of the crown-like spikes on its surface. There are four common human coronaviruses: 229E, NL63, OC43, and HKU1. Common human coronaviruses usually only cause mild to moderate upper-respiratory tract symptoms, such as the common cold. Those who contract these viruses are usually able to recover with only mild supportive medical assistance.

There are three other coronaviruses, which originate from animal sources and transfer to humans:

1. SARS-CoV (severe acute respiratory syndrome – coronavirus), which first appeared in southern China in November 2002;
2. MERS-CoV (Middle Eastern respiratory syndrome), which emerged in Saudi Arabia in 2012, but may have originated in Jordan; and
3. SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus-2), which originated in Wuhan, China in December 2019.

SARS-CoV-2 is the name given to the 2019 novel coronavirus. It is an enveloped, single-stranded, positive-sense RNA virus and is the cause of COVID-19, the resultant disease. COVID-19 results in death associated with acute respiratory distress syndrome (ARDS), usually as a result of pneumonia.

SARS-CoV-2 had not previously been identified in humans prior to its emergence in China in 2019. It is now understood that SARS2-CoV-2 originated in bats. The capacity for a disease to transfer from an animal to a human is called zoonosis, and the infection is called a zoonotic disease.

Researchers have demonstrated that SARS2-CoV-2 is 88% genetically related to two bat-derived SARS-like coronaviruses, (known as bat-SL-CoVZC45 and bat-SL-CoVZXC21), collected in 2018 in Zhoushan, eastern China. It is more distantly related to SARS-CoV (about 79%) and MERS-CoV (about 50%).

Other researchers have reported “nCoV-2019 is 96% identical at the whole genome level to a bat coronavirus.”

Current possible treatments.

There is considerable current interest in the use of hydroxychloroquine (HCQ) or chloroquine (CQ) as mitigating treatments for COVID-19.

Currently HCQ is used for rheumatoid arthritis and systemic lupus erythematous. It is also used for malaria, but only in areas where chloroquine is effective, such as the Caribbean and Central America. Due to increasing widespread resistance by P. falciparum and in P. vivax in Indonesia and the Pacific, chloroquine is used with diminishing frequency for malaria.

Chloroquine (a) differs from hydroxychloroquine (b) in that the latter has a hydroxyl group at the end of a side-chain. Hydroxychloroquine is a metabolite of chloroquine.19 20

This slight structural change has resulted in less toxicity for HCQ compared to CQ, notably less retinopathy. Rare cases of cardiomyopathy have also been reported with chloroquine.

The biological mechanism of CQ/HCQ.

There are several postulated mechanisms by which CQ/HCQ may act against SARS-CoV-2:

1. The virus is believed to enter a cell by binding to angiotensin-converting enzyme 2 (ACE2), which is found on the cell surface. The anti-SARS-CoV-1 action of CQ in vitro is attributed to an antagonist ACE-2 effect, thus impeding viral-cell surface binding.
2. CQ has also been shown to increase the endosomal pH, which may impair SARS-CoV early stage viral replication.

CQ/HCQ dosing:

A dose of hydroxychloroquine 600mg per day has been shown to achieve a concentration of 1ug/mL. It is unclear if this is a suitable therapeutic dose.

Gao (2020, Feb 19th) reported that “results from more than 100 patients have demonstrated that chloroquine phosphate is superior to the control treatment in inhibiting the exacerbation of pneumonia, improving lung imaging findings, promoting a virus negative conversion, and shortening the disease course…”

An uncorrected manuscript from Huang and co-workers (April 2020) gives a detailed analysis of chloroquine 500mg twice daily for 10 days (n= 10) compared to lopinavir/ritonavir 400/100mg (n=12) twice daily for 10 days as follows:

The first patient achieved lung clearance based on CT imaging was from the Lopinavir/Ritonavir group at Day 6 and this patient became SARS-CoV-2 negative at Day 3.

In the chloroquine group, the first patient achieved lung clearance was at Day 8 who became SARS-CoV-2 negative at Day 7… These data suggest that viral clearance does not translate immediately into pathological improvement in lungs. By Day 9, 6 patients (60%) in the Chloroquine group reached lung clearance, compared to 3 (25%) from the Lopinavir/Ritonavir group…

By Day 14, the incidence rate of lung improvement based on CT imaging from the Chloroquine group was more than double that of the Lopinavir/Ritonavir group (rate ratio 2.21, 95% CI 0.81-6.62).

These results suggest that patients treated with Chloroquine appear to recover better and regain their pulmonary function quicker than those treated with Lopinavir/Ritonavir.

During the chloroquine treatment period, there were nine adverse reactions in five patients including vomiting, abdominal pain, nausea, diarrhoea, rash or itchy, cough and shortness of breath. No serious adverse reactions were reported and there were no patient withdrawals. The serum concentration of chloroquine was in the range of 0.26 – 0.61μmol/L.

T-cell counts were taken for 10 CQ patients every two days. CD3+, CD4+, CD8+ counts showed no significant reduction in T-cell counts during the 10-days of treatment and chloroquine had no significant effect on immune capacity of patients.

Gautret et al. (March 20, 2020) published results of a limited trial which has been the genesis of much academic debate and criticism apropos of the use of HCQ to treat COVID-19. The researchers enrolled twenty-six COVID-19 positive patients who were PCR (polymerase chain reaction) documented SARS-CoV-2 carriers in nasopharyngeal sample at admission; and, 16 patients who refused treatment acted as negative controls. Six study patients were lost to follow-up.

Study patients received 600mg daily of HCQ (200mg three times a day). Nasopharyngeal viral load was tested daily in the hospital. Azithromycin was added if their clinical presentation indicated a need. The dose was 500mg on day 1 followed by 250mg per day for the next four days to prevent bacterial super-infection under daily electrocardiogram control.

Treated patients showed a significant reduction of the viral load at day 6-post inclusion compared to controls, as shown in the following graphs. Azithromycin added to HCQ was significantly more efficient for virus elimination.

Graph 1. PCR-positive samples in patients treated with HCQ (reproduced from Gautret et al)

Percentage of patients with PCR-positive nasopharyngeal samples from inclusion to day 6 post-inclusion in COVID-19 patients treated with hydroxychloroquine and in COVID-19 control patients.

Graph 2. PCR-positive samples in patients treated with HCQ +/- azithromycin (reproduced from Gautret et al)

Percentage of patients with PCR-positive nasopharyngeal samples from inclusion to day 6 post-inclusion in COVID-19 patients treated with hydroxychloroquine only, in COVID-19 patients treated with hydroxychloroquine and azithomycin combination, and in COVID-19 control patients.

This research has been criticised by Frie and Gbinigie of the Oxford COVID-19 Evidence Service Team. Weaknesses identified include:

1. A failure to recruit the 48 patients needed to achieve 85% power.
2. Therapy effect sizes could therefore, be exaggerated and false-positives generated. One patient tested virus negative on day 6 but positive on day 8.
3. There was insufficient medium to long-term follow-up.
4. The trial was not randomised; hence, allocation bias could have been introduced.

Azithromycin and alternatives:

Azithromycin, a bacteriostatic macrolide, is active against gram-positive and Gram-negative bacteria including Bordetella pertussis and Legionella species plus Mycoplasma pneumoniae, and Haemophilus influenzae. Since the 1990s, resistance has been increasing to Streptococcus pneumoniae and Staphylococcus aureus.

The literature contains numerous reports that highlighted a statistically significant increase in arrhythmia risks and mortality.

Against these reports was a retrospective observational study of scripts dispensed between 2000 and 2011 in South Carolina. The volumes dispensed were: 283,743 azithromycin; 143,191 amoxicillin; 52,714 clindamycin; 38,133 clarithromycin and 49,734 for the quinolones. The researchers concluded, “Our study shows that the odds of cardiovascular mortality between azithromycin and other antibiotics are not statistically significantly different and previous published findings may not be applicable to the general population.”

Notwithstanding this variance of findings, the Australian Medicines Handbook carries a caution linked to a prolonged QT interval. This accords with a 2012 advisory from the US Food and Drug Administration (FDA) to consider the risk of fatal heart rhythms in those:

• With a prolonged QT interval (including congenital long QT syndrome);
• Taking medicines that are likely to prolong the QT interval; or
• With a history of torsades de pointes, arrhythmias or uncompensated heart failure.

Because of these cardiovascular concerns, other clinicians reported to use doxycycline as an alternative to azithromycin, to avoid these problems.

Heneghan et al (Oxford COVID-19 EMB team) offer the following treatment options for community-acquired pneumonia (CAP):

Early use of antibiotics in older adults

Non-response to initial antimicrobial therapy increases mortality, and so the initial selection of antimicrobials is critical. According to NICE [National Institute for Health and Care Excellence], to cover atypical and multiple pathogens in older patients with pneumonia and at risk of severe complications, the recommended choices of antibiotics in the community are:

Amoxicillin with	500 mg 3 times a day (higher doses can be used …[consult appropriate references]) for 5 days
Clarithromycin (if atypical pathogens)	500 mg twice a day for 5 days

Alternative oral antibiotics for penicillin allergy, if the pneumonia is of moderate-intensity; treatment should be guided by microbiological results when available.

Doxycycline or	200 mg on the first day, then 100 mg once a day for a further 4 days (5-day course in total)
Clarithromycin	500 mg twice a day for 5 days

As they note, “viral infections increase pneumococcal adherence to the local epithelium, facilitating bacterial infection. Adhesion of Streptococcus pneumoniae to epithelial cells, for example, is significantly enhanced by human coronavirus HCoV-NL63 infection.”

A more comprehensive treatment regime from Up To Date is supplied as a separate document for reference and guidance.

Autopsy findings:

The following may be of clinical significance to the treating respiratory physician.

Pathologic findings from these two patients were edema and prominent proteinaceous exudates, vascular congestion, and inflammatory clusters with fibrinoid material and multinucleated giant cells. Reactive alveolar epithelial hyperplasia was seen in case 1, and fibroblastic proliferation (fibroblast plugs) in case 2 is indicative of early organization. No prominent neutrophil infiltration was seen. The significance of the large protein globules is not entirely clear, as these were described in patients with SARS but could also represent a nonspecific change with aging. More cases with sufficient controls are necessary to further clarify this change.

The two cases reported here represent “accidental” sampling of COVID-19, in which surgeries were performed for tumors in the lungs at a time when the superimposed infections were not recognized. These provided the first opportunities for studying the pathology of COVID-19.

Conclusion:

COVID-19 has been a pandemic since March 11, 2020. Four patients from Seattle, Washington received a trial vaccine in March 17, 2020 and Australian researchers hope to begin human trials in late April 2020, but the best estimates for full production place vaccine availability at mid-2021.

Very limited data suggests a possible role for hydroxychloroquine, with the addition of azithromycin or, if there is a poor cardiovascular profile, the use of doxycycline. At best, the role for HCQ is equivocal, with a leaning towards a possible benefit.

Against that background, clinicians have an onerous challenge.

HCQ is a known drug, having received FDA approval for use in lupus and rheumatoid arthritis in 1956. However, COVID-19 is reported to cause liver and renal injury, and HCQ is metabolised in the liver and present in the urine. This may make reaching the therapeutic dose of HCQ a challenge and increases the risk of adverse drug reactions.

Frequent monitoring of liver function and renal function in patients with COVID-19 would be imperative, to minimise any further damage whilst seeking to attain a therapeutic drug level.

Until more trial results are available HCQ – with the appropriate antibiotics and supportive medical care – may be one of the few therapeutic options available to avert patient death.

It is a hard choice and must be underpinned by the medical dictum primum non nocere – First, do no harm.

However, another factor must be weighed in the scales: “You go to war with the army you have, not the army you might want or wish to have at a later time.”

Respiratory infections can be transmitted via droplets expelled when an infectious person coughs, sneezes, talks, and breathes. These droplets can be classified according to size, with the World Health Organization (WHO) defining particles 5-10μm in diameter as droplets and particles less than 5μm as droplet nuclei. The classification of droplet size has important implications for how an infection may be spread and the most appropriate precautions to prevent transmission.

Due to their small size, droplet nuclei can remain suspended in the air for prolonged periods which enables transmission over relatively long distances (i.e. >1 metre). Conversely, larger droplets will fall to the ground much faster and travel a relatively short distance, although this may be affected by ambient airflow.

Current evidence suggests that the virus responsible for coronavirus disease (COVID-19) is primarily transmitted by droplet transmission. Droplet transmission is only likely to occur following close contact with an infectious person or through direct contact with a surface contaminated with droplets from an infectious person.  Hence, the importance of social distancing and improved hygiene practices. However, airborne transmission may be possible in aerosol-generating procedures such as tracheal intubation, cardiopulmonary resuscitation, and bronchoscopy. One activity that may be overlooked is the potential for nebulisers to transmit infection in this way.

Nebulisers are used in aerosol drug delivery and can produce particles less than 5μm in diameter. The Therapeutic Guidelines: Respiratory advise that nebulisers are not suitable for use in patients with acute infection due to the potential to spread infective organisms.

The Australian Department of Health advises that nebulisers should be avoided for the treatment of patients with suspected or confirmed COVID-19. Alternative modes of medication delivery should be considered for these patients. For short-acting beta₂-agonists, the evidence suggests that an equivalent bronchodilator effect is produced when inhaled via nebuliser or metered-dose inhaler (MDI) and spacer in most cases.

However, there are situations where the use of a nebuliser may be considered appropriate for patients with suspected or confirmed COVID-19. These clinical scenarios may include:

• Severe, life-threatening exacerbations of asthma;
• When forced expiratory volume in one second (FEV1) is less than 30% predicted;
• Patients with a history of poor response to MDI with spacer;
• Patients who are uncooperative or unable to follow the directions required for medication administration via MDI and spacer;
• Administration of certain medications for the treatment of cystic fibrosis; and
• Nebulised adrenaline for croup in children.

If medication must be delivered to a person with suspected or confirmed acute respiratory viral illness, actions should be taken to minimise the risk of viral transmission in accordance with hospital infection control policies. A negative-pressure area should be used, if possible. Alternatively, a single room with the door closed can be used to isolate the patient. Standard precautions should be instituted as well as airborne precautions, including P2/N95 respirator mask, eye protection, impervious gown, and gloves. The length of time that infectious particles remain in the air is dependent upon the rate of air change in the environment. However, airborne precautions should be continued for at least 30 minutes after nebuliser treatment has ended.

During the current coronavirus disease (COVID-19) pandemic, meticulous attention must be paid to infection control measures. Online learning modules covering a range of topics, such as hand hygiene and the appropriate use of personal protective equipment, are available at the Australian Commission on Safety and Quality in Health Care.

The following is a brief overview of the clinical course of coronavirus disease along with current and emerging therapies.

Clinical course of infection:

• Ranges from asymptomatic infection, mild upper respiratory tract illness and severe viral pneumonia with respiratory failure (ARS = acute respiratory failure).
• Typical symptoms include fever (>37.3⁰C), cough, sputum production and fatigue.
• Duration of viral shedding is 8-37 days (mean 20 days in survivors, continued until death in fatal cases).

Duration of symptoms:

• Fever duration median 12 days (range 8-13 days)
• Cough 19 days (12-23)
• Dyspnoea started average seven days after disease onset

Testing

• Throat swab specimens for polymerase chain reaction (PCR) test

Risk factors for poor prognosis, severe disease or ICU admission:

• Higher SOFA score (Sequential Organ Failure Assessment)
• D-dimer levels >1mcg/mL on admission

Risk factors associated with mortality:

• Advanced age – mean 69 years non-survivors (range 63-76) vs survivors mean 52 years (range 45-58)
• Higher frequency of complications
• Signs of sepsis
• Diabetes
• Coronary heart disease
• Hypertension
• Lymphopenia, leucocytosis (baseline lymphocyte count significantly higher in survivors)
• Elevated alanine aminotransferase (ALT), lactate dehydrogenase, troponin (high sensitivity), creatine kinase (CK), D-dimer, ferritin, interleukin-6 (IL-6), prothrombin time, creatinine, procalcitonin.

Complications:

• Sepsis
• Respiratory failure
• Heart failure
• Septic shock
• Ventilator-associated pneumonia
• Acute kidney injury (AKI)
• Acute respiratory distress syndrome (ARDS)
• Acute cardiac injury
• Pneumonia or bacteraemia (secondary bacterial infection)
• Coagulopathy (3-second extension of prothrombin time or 5-second extension of activated partial thromboplastin time (APTT))
• Hypoproteinaemia (albumin < 25g/L)

The following excerpt of drug treatments and emerging therapies is published in BMJ Best Practice – COVID-19, 2020:

Drug Treatments

Symptom relief: give an antipyretic/analgesic for the relief of fever and pain. There have been media reports stating that non-steroidal anti-inflammatory drugs such as ibuprofen could worsen COVID-19. However, there is currently no strong evidence to support this, and the situation is being monitored closely.

Antimicrobials: start empirical antimicrobials to cover other potential bacterial pathogens that may cause respiratory infection according to local protocols. Give within 1 hour of initial patient assessment for patients with suspected sepsis. Choice of empirical antimicrobials should be based on the clinical diagnosis, and local epidemiology and susceptibility data. Consider treatment with a neuraminidase inhibitor until influenza is ruled out. De-escalate empirical therapy based on microbiology results and clinical judgement. Some patients with severe illness may require continued antimicrobial therapy once COVID-19 has been confirmed depending on the clinical circumstances.

Corticosteroids: corticosteroids are being used in some patients with COVID-19; however, they have been found to be ineffective and are not recommended. The WHO (as well as other international pneumonia guidelines) do not routinely recommend systemic corticosteroids for the treatment of viral pneumonia or acute respiratory distress syndrome unless they are indicated for another reason. A randomised controlled trial investigating the use of corticosteroids in patients with COVID-19 is in progress.

Emerging therapies

Antivirals

Various antivirals (monotherapy and combination therapy) are being trialled in patients with COVID-19 (e.g., oseltamivir, lopinavir/ritonavir, ganciclovir, favipiravir, baloxavir marboxil, umifenovir, ribavirin, interferon alfa); however, there are no data to support their use. Results from one small case series found that evidence of clinical benefit with lopinavir/ritonavir was equivocal. A randomised controlled trial of approximately 200 patients in China found that treatment with lopinavir/ritonavir was not beneficial compared with standard care alone (primary outcome was time to improvement) in hospitalised patients with severe COVID-19. Remdesivir shows in vitro activity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and has been used to treat patients in China, as well as the first patient in the US. Clinical trials with remdesivir have started in the US and in China.

Intravenous immunoglobulin

Intravenous immunoglobulin is being trialled in some patients with COVID-19; however, there are no data to support this.

Chloroquine and hydroxychloroquine

Chloroquine and hydroxychloroquine are being trialled in some patients with COVID-19. Chloroquine shows in vitro activity against SARS-CoV-2. An expert consensus guideline in China recommends chloroquine in mild to severe cases of COVID-19 as it may improve the success rate of treatment, shorten hospital stay, and improve patient outcome.

Angiotensin-II receptor antagonists

Angiotensin-II receptor antagonists such as losartan are being investigated as a potential treatment because it is thought that the angiotensin-converting enzyme-2 (ACE2) receptor is the main binding site for the virus.

Convalescent plasma

Convalescent plasma from patients who have recovered from viral infections has been used as a treatment in previous virus outbreaks including SARS, avian influenza, and Ebola virus infection. A clinical trial to determine the safety and efficacy of convalescent plasma in patients with COVID-19 has started in China; however, there is no data on its use as yet.

Other drugs

Other drugs that may show promise for the treatment of COVID-19 include teicoplanin and camostat mesylate.

Atezolizumab is now available on the Pharmaceutical Benefits Scheme (PBS) for the first-line treatment of extensive-stage small cell lung cancer (ES-SCLC).

In the IMPOWER-133 trial, atezolizumab was used in conjunction with etoposide and platinum chemotherapy in ES-SCLC, opening up a new standard of care for these patients.

The median duration follow up was 22.9 months and atezolizumab was associated with a significant improvement in efficacy (median overall survival of 12.3 months versus 10.3 months; median duration of action of 4.2 months versus 3.9 months) compared to etoposide and platinum-based chemotherapy alone. In addition, 9.1% of patients demonstrated ongoing response with the triplet chemo-immunotherapy at clinical cut-off date compared to 2.3% of patients on chemotherapy.

The incidence of treatment-related adverse effects was similar between the treatment arms. However, immune-mediated adverse effects including hypothyroidism and hyperthyroidism, hepatitis, rash and infusion reactions were markedly higher with atezolizumab combination at 41.4% and chemotherapy at 24.5%.

Xerostomia is a subjective feeling of a dry mouth associated with dysfunction of the salivary glands that affects around 10% of the general population. The salivary glands are located around the mouth and throat. These glands normally produce 1-1.5L of saliva each day. The protective role of saliva includes keeping the mouth moist at all times, lubrication during the chewing process, and prevention of tooth decay and other gum diseases. Saliva also helps with the formation of sounds in speech.

Xerostomia is a symptom of an underlying problem rather than a disease in itself. Approximately 70% of the patients have a systemic cause.

Primary xerostomia is caused by:

• Salivary gland atrophy due to ageing. Approximately 25% of older adults have a dry mouth symptom;
• Salivary gland infections. For example, mumps can cause gland inflammation and disrupt the saliva flow; and
• Autoimmune salivary gland disease. For example, Sjögren’s syndrome is an autoimmune disease that causes dry eyes, dry mouth and arthritis.

Secondary xerostomia can be caused by:

• Mouth breathing. For example, sinusitis causing a blocked nose or women going through hormonal changes during pregnancy or menopause;
• There are many medications that can cause dry mouth. These drugs include antidepressants (especially tricyclic agents), diuretics, anticholinergics, tranquilisers, antihistamines, antiemetics, antihypertensives, some antimigraine drugs, anti-parkinson drugs, lithium, and opioids. Illegal drugs such as cocaine are also known to cause dry mouth;
• Depression and anxiety. For example, giving a speech in public;
• Dehydration, which can be simply due to drinking little fluid or related to a medical condition such as diabetes, diarrhoea or kidney failure;
• Anaemia due to iron, folate and vitamin B12 deficiency; and
• Cancer treatment such as chemotherapy or radiotherapy at the head or neck disrupts the functions of salivary glands to produce saliva.

The consequences of xerostomia can lead to reduced saliva flow which may affect speech, cause difficulty in swallowing food, and increase the risk of tooth decay, mouth ulcers, and infections such as oral thrush (Candida albicans). Patients can also find it difficult to attach dentures to the gum.

Symptoms of dry mouth include a decrease in taste, bad breath, having a rough and dry tongue, and a burning sensation on the tongue.

Treatment of dry mouth must include finding the cause which should be treated as early as possible. If medications are the cause of the dry mouth, a review of drug therapy is necessary. Saliva substitutes such as Aquae^® or dry mouth products such as Biotene^® may be used. These products come in a range of forms including toothpaste, oral spray, topical gels, and mouthwash.

Patient education should include dietary information and promotion of good oral hygiene. Regular dental check-ups should be encouraged. Patients should also be advised to avoid taking certain medications such as decongestants and antihistamines as well as avoiding alcohol, caffeine, and tobacco smoking which can increase mouth dryness.

Other strategies to consider include:

• Chew sugarless gum to stimulate the saliva flow;
• Sip sugarless fluids frequently to keep the oral membrane moist;
• Use sodium fluoride 0.5% mouthwash for 5 minutes every day; and
• Use a topical application of moisturiser to lips.

There are many drugs available for the prevention of frequent migraines. For the most part, they are medications that have been developed for other conditions such as depression or epilepsy. However, a number of injectable compounds have recently been developed specifically for migraine prophylaxis. These include erenumab and the newly registered fremanezumab and galcanezumab. These monoclonal antibodies all block the activity of calcitonin gene-related peptide (CGRP).

The precise pathogenesis of migraines is not entirely understood. However, current thinking describes migraine as a predominantly neural disorder with any vascular changes considered likely to be secondary. The trigeminal system is particularly important for the progression of migraine signals and CGRP is the most abundant peptide in this system. Release of CGRP initiates a cascade that includes the increased production of nitric oxide, sensitisation of nociceptive neurons, and vasodilation.

Studies demonstrate that people who suffer from migraines are unusually sensitive to CGRP. Intravenous injection of CGRP was shown to induce migraine-like headaches in migraine sufferers, while only producing mild headache or discomfort in non-migraine sufferers. Additional evidence to implicate the importance of CGRP in migraines includes the findings that triptan medications reduce CGRP levels as pain relief occurs. Studies demonstrate that around two-thirds of migraine sufferers respond to CGRP antagonists, suggesting that different aetiologies are involved in migraine headaches.

While these three monoclonal antibodies all reduce the activity of CGRP, they achieve this end in a slightly different way. Fremanezumab and galcanezumab potently and selectively bind to the CGRP ligand to prevent it from interacting with the CGRP receptor. The association with CGRP occurs rapidly for each medication. However, while fremanezumab dissociates from its target very slowly, galcanezumab does so rapidly. This rapid dissociation may allow significant levels of CGRP to remain free to interact with the receptor. In contrast, erenumab is an antagonist at the CGRP receptor that potently and specifically competes with CGRP. The end result of all three medications is reduced activation of the trigeminal system.

Like all monoclonal antibodies, these agents are large molecules. It is, therefore, unlikely that these agents could cross the blood-brain barrier to any great extent. Instead, it is thought that the peripheral vasculature is the likely site of action. Studies demonstrate that these agents are effective in inhibiting CGRP-induced neurogenic vasodilation in the middle meningeal artery, but not of the pial artery. The middle meningeal artery, the main supplier of the dura mater, is located outside of the blood-brain barrier. Studies demonstrate that at the onset of migraine, it is this artery that increases in circumference more on the pain side than the non-pain side.

Erenumab, fremanezumab, and galcanezumab are all intended for subcutaneous injection. They have long half-lives (27 days, 31 days, and 28 days respectively) which allows for monthly dosing. Fremanezumab is also approved in a higher strength product for administration every three months. This may offer compliance advantages for patients when compared to other prophylactic agents that must be taken daily. Adherence to daily prophylactic medications is thought to be low in this population. Studies suggest that adherence at six-months may be as low as 26% and reduce further to 17% at 12 months.

All three monoclonal antibodies are presented in prefilled devices suitable for self-administration. Local reactions at the injection site were the most commonly reported adverse reactions for all three agents. There is limited data on safety and efficacy of use beyond 12 months, although no signals or trends have currently been identified that suggest a potential problem. Some concerns have been raised regarding the long-term blockade of CGRP due to its variety of biological functions. CGRP is known to have a protective role in the cardiovascular system and possibly also the gastrointestinal system. There is particular concern that CGRP blockade could inhibit protective vasodilatory responses to cerebral and cardiac ischaemia. One placebo-controlled study of erenumab in a high-risk cardiovascular population may allay some of these fears. In this study, erenumab did not adversely affect exercise time which suggests that CGRP blockade may not worsen myocardial ischaemia. It has also been theorised that targeting the CGRP ligand, as occurs with fremanezumab and galcanezumab, may be safer as it allows the receptor to still interact with other ligands important in biological functions.

These medicines are not currently listed on the Pharmaceutical Benefits Scheme (PBS). However, galcanezumab recently received a positive recommendation from the Pharmaceutical Benefits Advisory Committee while a decision for fremanezumab was deferred. The newly launched Medicine Status Website can be used to track the status of these medicines as they move through the PBS listing process.