While prevention is better than cure and vaccines remain the best frontline defence, Cathy O’Leary looks at growing interest in ways to treat COVID-19.

Just as the development of vaccines for COVID-19 has occurred at lightning speed relative to other drugs, the growing arsenal of antivirals to treat the disease is also forging ahead.

While Australia is still focused on reaching high COVID-19 vaccination targets, particularly in WA where rates lag, treatment options for the virus are set to become increasingly important as the country starts to live with the disease.

Many health experts believe the key to finding successful treatments is to keep widening the net, particularly when there is still limited evidence of the effectiveness of some drugs.

Australia’s dedicated COVID treatments – remdesivir and sotrovimab – are currently being used to treat patients across the country, while the Federal Government has signed up to buy 300,000 courses of molnupiravir, which is yet to be approved by the Therapeutic Goods Administration.

Molnupiravir, originally developed to treat influenza, is a capsule that is taken twice a day for five days by adult patients with mild-to-moderate COVID symptoms.

It has the advantage of not needing to be refrigerated, allowing it to be used in the community or as a targeted intervention at high-risk locations and in rural areas.  It is also considerably less expensive than some treatments that require intravenous transfusions.

According to its developer Merck, molnupiravir could halve the chances of dying or being hospitalised in those people most at risk of contracting severe COVID. So far, the drug has only been granted a provisional determination by the TGA, the first step in the approval process.

If it gets the green light, molnupiravir could be available early in the new year, under an advance purchase deal struck between the Commonwealth and manufacturer Merck Sharp & Dohme.

Meanwhile, Pfizer Australia has confirmed it will supply at least 500,000 treatment courses of its investigational COVID oral antiviral candidate, provided it passes ongoing phase 2-3 clinical trials and is approved by the TGA.

Should it prove effective, the treatment, known as PF-07321332, would be administered in combination with HIV protease inhibitor ritonavir as an early treatment or potential prophylaxis for people exposed to COVID.

According to Pfizer, this combination, Paxlovid, is the first orally administered experimental drug to be evaluated in clinical trials to specifically target COVID-19. 

It is designed to slow the virus by blocking the activity of the main SARS-CoV-2 protease, an enzyme essential for viral replication. Its clinical trials are ongoing.

The drug would be used in combination with ritonavir, which would help break down PF-07321332 so it is active for longer.  

The Pfizer drug is expected to be made available over the course of next year, but its availability still depends on the results of trials as well as the TGA approval. 

Australia is also expecting to be supplied during 2022 with 15,000 doses of the breakthrough Roche antibody-based treatment, Ronapreve, which is likely to be used intravenously for COVID patients in hospital.