A new Covid antiviral is being rolled out but how well does it work?

ITV News Science Editor Deborah Cohen reviews the potential impact of the antiviral drug

Throughout the Covid pandemic health leaders have been worried about the NHS becoming overwhelmed and so a drug that promises to cut the risk of hospitalisation or death by 88% in high risk people compared to a placebo if taken within five days is something to be excited about. It would dramatically reduce people’s risk of becoming very ill and also limit coronavirus’ burden on the NHS. And a drug called Paxlovid, made by US drug company Pfizer, is being rolled out to high risk patients that promises to do just that.

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ITV News caught up with Professor Stephen Powis, medical director of NHS England. He said that more than 5,000 people had received the drug, with more than one million people eligible. Cathy Merry has rheumatoid arthritis and takes drugs to suppress her immune system that makes her vulnerable to Covid. She has lateral flow tests at home to see if any illness she has is Covid. “Seeing that positive test made me feel rather angry because we realised that after being careful for so long we managed to contract Covid," she says. After her positive test she phoned her doctor, who prescribed her this new antiviral. “They put them in a taxi and within 24 hours of testing positive and feeling unwell, I had the drugs ready to go", Cathy says. And this is key. These antivirals need to be given within five days of onset of symptoms - or ideally three days - for them to work as promised. And that can be a challenge for a stretched NHS - spotting symptoms; testing positive; getting a prescription and starting to take it in a short window. “Speed is of the essence so the sooner we get the drugs to people who might benefit, the better", Prof Powis says. All drugs have benefits and harms. And one particular concern is this drug can have harmful interactions with other drugs - and people with other illnesses who are vulnerable to Covid may be taking a mix of drugs.

Prof Powis says the NHS is well aware of these interactions and clinicians from the treatment units will call patients to discuss with them whether Paxlovid is right for them in their particular circumstances. But there is some debate in medical circles about quite how much people will benefit from Paxlovid. The trial for Paxlovid was carried out on people who had not been vaccinated nor had had Covid infection. But the UK looks quite different now. Dr Andrew Hill, a pharmacologist at Liverpool University is one of those people questioning Paxlovid. Many people who are vulnerable have been vaccinated and may have had Covid, so their risk of getting very sick and hospitalised has changed, Dr Hill says.

“You would expect people who are vaccinated to get less benefit from these drugs. The vaccines are already lowering their risk of hospitalisation," Dr Hill adds, so there's a question of how much benefit it will actually bring to people.

He says it might be the right thing to give the drug to vulnerable people, but we need to work out if it benefits them.

“In just two years into the pandemic not only do we have highly effective vaccines, but we have highly effective drugs. That’s a remarkable achievement by the scientific and clinical community. But of course we still need to know more, we still need to do more clinical trials,” Prof Powis told ITV News. “Going forward it’s important we know that these drugs are effective in people who’ve received their first vaccination and boosters as well," he adds. It was a similar situation with another antiviral called Molnupiravir. To work out the extent to which people here and now benefit from it, a publicly-funded trial called Panoramic is being run by Oxford University.

Dr Hill says these big independent trials are crucial to help us understand how these drugs work and Prof Powis says that Paxlovid will be included in the Panoramic trial too. The government has bought 2.7 million doses and Dr Hill estimates about £1 billion has been spent on it - and he says it’s not clear if it's worth the costs given there’s some uncertainty about the benefit people get from it. Dr Hill also points to the fact that Pfizer ran two clinical trials. Only one has been published in full - showing the reduction in hospitalisations or death in unvaccinated high risk people. But he says that we don’t yet have the full publication from a trial in low risk unvaccinated adults and those who have been vaccinated who have risk factors.

The company announced in a press release that there was no difference in the time it took for them to get better.

“The second study actually failed its primary objective, which was to look at the time it takes people to recover", Dr Hill says, adding: “We need to have the full picture to make sure that we can make the right judgments about these drugs.”

ITV News asked Pfizer when they were going to publish the full results.

Pfizer replied: "We do not have the results from the EPIC-SR study as the trial is ongoing. We will be able to share the results upon completion of the study, which is anticipated later this year."