An anti-viral pill for Covid-19, which was approved for use in the UK, needs a “rethink” because of the Omicron variant, England’s chief medical officer has said.
Molnupiravir, which can be taken at home, is for people who have had a positive Covid test and have at least one risk factor for developing severe illness, such as obesity, being over the age of 60, diabetes or heart disease.
Professor Chris Whitty said its rollout needs to be reconsidered to make sure it is targeted “in the right direction”.
It was approved for use in the UK on November 4.
Prof Whitty told a Downing Street press conference on Saturday: “On the anti-virals, we are going to have to do a bit of a rethink on the basis of this new variant, just to be confident we’ve got the right indications from it.
“There’s a variety of ways you could use it in different ways, and what we need to make sure is whatever stock we’ve got of these, what appear to be highly effective drugs, that we use in the most effective way and for the right people.
“Where you are in the pathway right from the very beginning… working out their place, we do need to think through and I think we probably need to do a rethink of it just to make sure with the new variant, we’re targeting in the right direction.”
The UK’s Medicines and Healthcare products Regulatory Agency (MHRA) had previously said the drug is safe and effective at reducing the risk of hospital admission and death in people with mild to moderate Covid who are at extra risk from the virus.
The drug, from Ridgeback Biotherapeutics and Merck Sharp & Dohme (MSD), works by interfering with the virus’s replication and prevents it from multiplying by keeping levels low in the body.
It was announced last month that 480,000 courses of molnupiravir had been secured after a study found it cut the rate of hospital admission and death by 50% in mild to moderately ill patients who had at least one risk factor for the disease.
The UK was the first country in the world to approve it for use, and it was described as a “gamechanger” by Health Secretary Sajid Javid.
Paul Hunter, professor in medicine at the University of East Anglia, said: “How much Omicron would impact on the anti-viral use depends largely on the anti-viral.
“I suspect that most effective therapies such as dexamethasone would not be particularly affected by Omicron as this drug targets the body’s response to the virus, not the virus.
“Drugs that inhibit viral replication, such as the recently licensed molnupiravir, could drive mutation of the virus such that Covid develops anti-viral resistance – we do see this with anti-virals with other viruses.
“However, it would be surprising that such anti-viral resistance would develop before use of these drugs. Consequently I doubt Omicron would be more resistant to this class of anti-virals.
“However those drugs that are based on monoclonal antibodies are likely to be less effective against a heavily mutated virus.
“I personally do not think that the Omicron will dramatically affect our treatment strategies, with the exception of the monoclonal antibodies, because of their probable reduced effectiveness.”