COVID antiviral drugs Paxlovid and Lagevrio to be divvied up, with priorities being set

Medical experts hope the two oral drugs - nirmatrelvir/ritonavir (brand name Paxlovid, made by Pfizer) and molnupiravir (brand name Lagevrio, made by Merck Sharpe and Dohme) - will save lives.

Almost 4000 people have died in Australia since the pandemic began.

Peter Wark, a University of Newcastle conjoint professor and senior staff specialist with John Hunter Hospital in NSW's Hunter region, said the antivirals would be available soon.

The federal government has purchased 500,000 courses of Paxlovid and 300,000 courses of Lagevrio.

This means there is a limited supply, with health officials tasked to decide who will receive them.

"There have been meetings to decide how to best utilise these medicines and how to administer and supply them to people," Professor Wark said.

Professor Wark said health officials had "a sensible gatekeeper role to play here".

"There will be limited supply, so there has to be a fair and transparent system. At the moment, we will want to target those people at the highest risk from COVID-19."

Sotrovimab - the monoclonal antibody drug that works against Omicron - is being used for unvaccinated people, including those unable to be vaccinated, and the immunosuppressed.

This drug is also being used for people at high risk of severe disease from COVID because of their age and/or serious underlying health conditions.

Criteria for the antivirals has not been decided, but "these same factors will be considered".

Asked if some boosted people with health conditions would get the chance to use the antivirals for early COVID treatment, Professor Wark said "they will be applied fairly and considered on an individual basis" against the planned criteria.

The antiviral drugs and monoclonal antibodies are given to COVID patients within the first week of the disease. The aim is to stop it progressing and prevent hospitalisation and death.

Eligible people will be offered access to these treatments when they record positive PCR tests or register their positive rapid antigen tests with the NSW government.

Some question whether anti-vaxxers could be offered access to the drugs ahead of some boosted people with underlying health conditions.

"We have to realise that the majority of people will be well protected by being vaccinated, and are not at risk of serious outcomes from COVID-19," Professor Wark said.

Nevertheless, some people are dying from COVID despite being double- or triple-vaccinated.

The nature of COVID, vaccination and waning immunity means some people could face severe disease and death without the option of using the antiviral drugs.

Relatively small clinical trials showed the antiviral drugs reduce hospitalisation. However, Professor Wark said "we don't have clear clinical trial data to suggest how effective they're going to be".

"Both trials gave the medication to people at risk of complications from COVID-19, usually with a serious health condition, but none of the people in the trials were vaccinated," he said.

The trials involved older people and those with a comorbidity, such as diabetes or obesity.

"So, in all fairness, it's not quite so clear how much benefit these antiviral drugs' will have in a highly vaccinated population. We obviously know that newer COVID variants will come along and vaccine protection varies to some extent."

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Nevertheless, Professor Wark said health officials want to offer the drugs "sensibly and for those in whom they hopefully will do the most good".

And the federal government may purchase more supplies.

"We want to make sure systems are in place, so everyone has the option to get it," he said.

But he cautioned against the drugs being considered a silver bullet.

"People will unfortunately continue to die from COVID, despite our best efforts. That's inevitable. But we want to help as many as possible," he said.

The drugs are expensive. Lagevrio reportedly costs US$700 per course, with Paxlovid priced at about US$530 per course. The price the government is paying for these drugs in Australia is unclear. They will be provided free to the public.

A sotrovimab treatment in the US costs about $2100.

Professor Wark said it wasn't practical or affordable for everyone in Australia to receive an expensive course of antiviral drugs to treat COVID.

He said the two new antiviral drugs and sotrovimab had been provisionally approved by the TGA. "This means they haven't been officially approved, so they are not available on the PBS," he said.

When the TGA granted provisional approval for the two antiviral drugs last month, it said they were "for the treatment of adults with COVID-19 who do not require initiation of oxygen and who are at increased risk of progression to hospitalisation or death".

"Neither product is intended to be used as a substitute for vaccination against COVID-19."

Professor Wark said the antivirals "must be used wisely".

It's possible that the drugs could lead to virus resistance and the emergence of new COVID variants.

"We should not assume the virus won't develop resistance to them, like bacteria do with antibiotics. If used unwisely, that's a risk," he said.

He added that some of these drugs "have interactions with other drugs".

The difficulty with sotrovimab is the logistics of having to administer an intravenous infusion in hospital.

"If we give that to people early in their illness, say within the first seven days and they're unvaccinated, we reduce their hospitalisation by about 60 per cent," Professor Wark said.

"But we don't know what impact that will have on someone who is vaccinated. We have been trying to target individuals we think are most likely to benefit.

"It is being done. We've brought people into John Hunter Hospital, generally the COVID ward. They've had their infusion and gone home."

Barriers preventing sotrovimab's use in aged care should ease for the oral antivirals.

Some have questioned why governments around the world have not given as much attention to the early treatment of COVID, as they have to vaccination.

The federal Department of Health, though, states that the clinical evidence taskforce does not recommend early treatments like "ivermectin, doxycycline or zinc outside of properly conducted clinical trials with appropriate ethical approval".

Despite this, some GPs have been prescribing doxycycline (an antibiotic) and zinc to asthma patients with COVID.

Japanese pharmaceutical company Kowa Co Ltd said on Tuesday that the cheap anti-parasite drug ivermectin shows an "antiviral effect" against Omicron and other coronavirus variants in joint non-clinical research.

However, several clinical studies for ivermectin have had conflicting results, with "some showing benefit, some no benefit".

"At this stage there is no evidence that any of these treatments work against COVID-19 and they should not be used outside of a clinical trial," Professor Wark said.

He said widespread vaccination is the most important tool to protect a population from COVID. Mask-wearing, social distancing and improved ventilation were also important to reduce the spread of the virus.

"Early treatments will have their place, but they will never replace these measures."