This week, Pfizer published data from a new study suggesting its oral COVID treatment pill (nirmatrelvir, brand name Paxlovid) reduces the risk of severe disease by 89%, according to the company’s phase 2-3 trial.
Australia’s Therapeutic Goods Administration (TGA) provisionally approved the pill for use in here in January, and the Australian Government has already secured access to 500,000 treatment courses of Paxlovid for supply in 2022.
A total of 2,246 patients were involved in the double-blind, randomised controlled trial, with 1,120 receiving the pill and 1,126 receiving a placebo.
There are all sorts of other medicines being used to treat COVID-19, including the injectible Remdesivir, the only antiviral drug approved to treat moderate-to-severe COVID in adults who aren’t on ventilation. But the promise of an oral COVID pill is its ease; it’s quick, simple, and can – at least physically – be administered by almost anyone. It could be a key frontline solution, especially for vulnerable people in remote areas or those who can’t be moved to larger hospitals.
“There are some specific cases that highlight how important they can be,” says Paul Griffin, an infectious diseases expert at the University of Queensland. “Most importantly aged-care settings where it can be hard to get those people to hospital for intravenous therapies.
“Being able to give them something that reduces their chances of progressing to severe disease and hospitalisation is going to really change things in my opinion.”
So, how do COVID treatment pills actually work?
According to the TGA, the nirmatrelvir component of the Paxlovid pill blocks the activity of a protease enzyme that coronavirus needs in order to replicate. Nirmatrelvir is combined with a low-dose of ritonavir, which maintains plasma levels of the nirmatrelvir for the duration of treatment.
And Paxlovid isn’t the only oral COVID treatment coming to – or already on – the market.
The TGA approved another oral pill, Molnupiravir (brand name Lagevrio), at the same time as Paxlovid. The pill, which was originally developed by Merck and Ridgeback Biotherapeutics to treat influenza, works similarly to inhibit replication of the virus. Preliminary results from October last year suggested the pill reduced the risk of hospitalisation or death by approximately 50% compared with placebo.
“Molnupiravir works in another way that sounds really cool,” says Griffin. “It causes lots of errors in reproduction … it causes viral error catastrophe, so the progeny are non-viable and that stops it being able to reproduce.”
The drugs are part of a new world-order in treating COVID; now we have tools we can use easily and widely to both prevent and treat the disease.
When will they roll out, and who will get access to these COVID-busting pills?
As reported by the RACGP earlier this month, the pills are unlikely to be widely available in the immediate term. New clinical guidelines for use in Australia specify they should be used in the early stages of the virus in unvaccinated adults who are at higher risk of serious disease progression. That’s because the trials did not include people who had received two vaccine doses, so their efficacy is less clear for vaccinated patients.
The Department of Health has stated that the pills should be reserved primarily for use among the most at-risk groups, including in residential aged care facilities and Aboriginal community-controlled health services.
Griffin says there’s not yet clarity on how exactly the rollout will work: “We’re hearing that aged care facilities have actually been delivered some of these products, but they’re not clear on who’s going to prescribe them, and there’s a bit of a gap at this stage in terms of exactly who’s best suited to receive these agents.”
In fact, the pills aren’t on the Pharmaceutical Benefits Scheme (PBS) yet, so there are still a number of steps to be finalised.
“What we don’t want to do is come up with a complicated system that requires input from hospital specialists to approve it in the community, when the whole idea is that it’s community-focused and can be administered rapidly,” Griffin says.
“So, I think we need to address some of these logistical challenges quite quickly.”
Most importantly, these pills aren’t meant to be preventative, or a vaccine substitute – they should be administered within five days of the onset of symptoms, with the goal of preventing the disease from progressing further.
“They’re not a replacement for vaccination,” Griffin says. “They’re very much a supplementary tool in people who still go on to get infected and are high risk and need additional help to reduce their chance of progressing to severe disease.
“In no way do they reduce the importance of vaccinations.”