The results of Pfizer’s study appear to surpass those seen with Merck’s own Covid pill, which was shown last month to halve the likelihood of dying or being hospitalised for patients also at high risk of serious illness.
A second antiviral pill for Covid-19 cuts rates of hospitalisation and death by nearly 90 per cent among at-risk patients with mild to moderate infections, according to early trial results.
The drug, if taken early enough, prevents the escalation of disease to keep newly-infected people out of hospital. Manufactured by Pfizer, the at-home pill is targeted at the elderly and those with underlying health conditions that make them vulnerable to Covid.
Britain has ordered 250,000 courses of the treatment, which will need to be approved by the UK’s medicines regulator before it can be given to patients.
Pfizer said preliminary data from its trial “suggest that our oral antiviral candidate, if approved by regulatory authorities, has the potential to save patients’ lives, reduce the severity of Covid-19 infections, and eliminate up to nine out of 10 hospitalisations.”
If the results stand up to scrutiny, the treatment, which consists of three pills given twice daily, could help to alleviate pressure on health services in countries and communities with low vaccination rates.
Pfizer’s study looked at hospitalisations or deaths among 775 unvaccinated people diagnosed with mild to moderate Covid-19. Patients had at least one risk factor for developing severe disease, such as obesity or older age. Treatment began within three to five days of the development of symptoms, and lasted for five days.
It found that 0.8 per cent of those given Pfizer’s drug within three days of symptom onset were hospitalised. None had died by 28 days after treatment. This compared with a hospitalisation rate of seven per cent for those patients given a placebo. There were also seven deaths within this group.
Rates were similar for patients treated within five days of symptoms: one per cent of the treatment group was hospitalised, compared with 6.7 per cent for the placebo group, which included 10 deaths.
Pfizer has not yet detailed side effects of the drug, but said adverse events happened in about 20 per cent of the treatment and placebo patients.
Upon the recommendation of an independent group of experts, the study was cut short due to the positive nature of the interim results, with Pfizer announcing that it would be seeking immediate authorisation from international regulators for use of its drug. Full trial data are expected to be published at a later date.
The drug is a protease inhibitor and was originally developed for SARS-CoV-1 in 2003 – the viral predecessor to Covid. It is designed to block an enzyme the coronavirus needs in order to multiply within the body. Merck’s pill works differently, by introducing errors into the genetic code of the virus.
The announcement of Pfizer’s trial results come a day after the UK’s Medicines and Healthcare products Regulatory Agency approved Merck’s Covid pill, known as molnupiravir, making it the first regulator in the world to do so. The UK has purchased 480,000 courses of the treatment, with the first deliveries expected this month.
