The first antiviral drug to save the lives of patients admitted to hospital with Covid-19 has been found by researchers.
The international Recovery trial demonstrated that an antibody combination developed by Regeneron Pharmaceuticals reduced the risk of death when given to patients with severe infections who had not mounted a natural antibody response of their own.
These patients' chances of needing to be put on a ventilator were also reduced, along with the duration of their hospital stay.
Between September 18, 2020 and May 22 of this year, 9,785 UK patients admitted to hospital with Covid-19 were randomly allocated to receive usual care plus the antibody combination treatment, or the usual care alone.
Of these, about one third were seronegative, meaning they had no natural antibody response of their own, and half were seropositive, meaning they had already developed natural antibodies against the virus.
For one sixth of those involved in the study, their serostatus was unknown.
Researchers found that among patients who received the usual care alone, 28-day mortality was twice as high in those without an antibody response (30 per cent) compared with those who were seropositive (15 per cent) at the start of the study.
In patients who had no antibody response, the treatment reduced the chance of them dying within 28 days by a fifth, compared with the usual care alone.
This led the researchers to conclude that for every 100 such patients treated with the antibody combination, there would be six fewer deaths.
The results were described as "very exciting" by Sir Peter Horby, professor of emerging infectious diseases in the Nuffield Department of Medicine, University of Oxford, and joint chief investigator for the Recovery trial.
“The hope was that by giving a combination of antibodies targeting the Sars-CoV-2 virus we would be able to reduce the worst manifestations of Covid-19," he said.
“There was, however, great uncertainty about the value of antiviral therapies in late-stage Covid-19 disease.
“It is wonderful to learn that even in advanced Covid-19 disease, targeting the virus can reduce mortality in patients who have failed to mount an antibody response of their own.”
The antiviral treatment has yet to be approved for use in the UK, and any introduction will be slow because the drug is not particularly easy to get hold of.
Another obstacle is antibody testing, which patients would require on their admission to hospital but is not currently in place.
The study, which is yet to be peer reviewed, received a warm welcome from England's National Health Service. The statutory board on Tuesday asked the NHS to quickly set up a new monoclonal antibody service before offering the antivirals should they receive approval.
