An antiviral pill was found to cut hospitalisations and deaths by half in patients newly diagnosed with Covid-19, in clinical trial results announced on Friday.
If approved, the drug made by the US firm Merck and Ridgeback Biotherapeutics would be the first simple oral medication shown to be effective against Covid-19 and a major advance in the fight against the pandemic. Other drugs, such as remdesivir, have been shown to be effective if given early, but all currently approved treatments need to be given as injections or IV infusions.
Merck said it would apply for emergency use authorisation for the drug in the US within the next two weeks and seek the green light for use in several other countries. Experts predicted that, if further data supports the initial results, the pills could be approved for treating high-risk patients within weeks of an application being made.
“It exceeded what I thought the drug might be able to do in this clinical trial,” said Dean Li, the vice-president of Merck research. “When you see a 50% reduction in hospitalisation or death that’s a substantial clinical impact.”
The trial tracked 775 adults with mild to moderate Covid, who were considered higher risk for severe disease owing to health problems such as obesity, diabetes or heart disease. Half were given a five-day course of the pill, called molnupiravir, which come in the form of small brown capsules taken twice a day. In the placebo group, 53 patients (14%) were hospitalised compared with only 28 (7%) of those who received the drug. There were no deaths in the drug group after that time period compared with eight deaths in the placebo group, according to Merck.
The data from the study was made public in a press release and has not yet been peer-reviewed. However, an independent group of medical experts monitoring the trial recommended stopping it early because the interim results were so encouraging.
Prof Peter Horby of the University of Oxford, who co-led the UK’s Recovery trial which identified the first life-saving drug to treat Covid, said: “It’s really encouraging to see some positive clinical data in a trial. If the results hold out this would be a very positive result.”
Horby said the drug “ticks a lot of boxes” – in particular it comes in pill form and appears to have a good safety profile. However, he said “one has to be a little cautious” over the precise efficacy rate as with small numbers these figures can wobble up and down based on the outcomes of just a handful of patients.
Only limited information on side-effects was made public in the press release, but the company said rates were similar between the placebo group and the treated group. An adverse event, or bad outcome, occurred in 35% of those who received molnupiravir and 40% of those who received placebo. Only 1.3% of participants who received the drug discontinued treatment because of an adverse event, compared with 3.4% who discontinued the placebo.
A convenient pill that patients could take when Covid symptoms first appear has long been viewed as a crucial goal in controlling future waves of infection and reducing the ongoing impact of the pandemic. Finding at least two such treatments by the end of the year was identified as a goal of the UK government’s antivirals taskforce when it was launched in April, with a view to deploying the drugs over the winter. The Department of Health and Social Care has not confirmed whether the UK has preordered doses of the drug.
The company has said it will use a “tiered pricing approach”, pricing the drug to reflect countries’ ability to pay for it.
Penny Ward, a visiting professor in pharmaceutical medicine at King’s College London, said: “The availability of a well-tolerated, effective oral antiviral will be particularly useful in supplementing vaccination as a means to reduce the proportion of patients needing hospital care. It is greatly hoped that the antiviral taskforce has, like the vaccines taskforce, preordered courses of this medication so that the UK can, at last, properly manage this condition by treating vaccine breakthrough disease and relieve pressure on the NHS during the forthcoming winter.”
Molnupiravir works by creating errors in the virus’s RNA, which impairs its ability to replicate. This means it is only likely to be effective if given in the early stage of infection when the virus is still multiplying in the body – in the trial, it was given within the first five days of symptoms.
Covid infection rates are still mixed across the UK, according to the latest data from the Office for National Statistics. An estimated one in 85, or 658,800 people, would have tested positive in England in the week ending 25 September, up from one in 90 or 620,100 the week before. Infections are up marginally in Wales too, from one in 60 to one in 55, but down slightly in Northern Ireland and Scotland, where rates are one in 65 and one in 55 respectively.
Cases are rising steeply among children at secondary school, where 4.6% would have tested positive in the week surveyed, up from 2.7% two weeks earlier. While cases overall are falling in London and the north-east, they are rising in the north-west, Yorkshire and the Humber, the East Midlands and the south-west.