(Reuters) -Pfizer Inc said on Monday it has started a large study testing its investigational oral antiviral drug for the prevention of COVID-19 infection among those who have been exposed to the virus.
The drugmaker and its rivals, including U.S.-based Merck & Co Inc and Swiss pharmaceutical Roche Holding AG (OTC:RHHVF), have been racing to develop an easy-to-administer antiviral pill for COVID-19.
The mid-to-late-stage study will test Pfizer (NYSE:PFE)'s drug, PF-07321332, in up to 2,660 healthy adult participants aged 18 and older who live in the same household as an individual with a confirmed symptomatic COVID-19 infection.
In the trial, PF-07321332, designed to block the activity of a key enzyme needed for the coronavirus to multiply, will be administered along with a low dose of ritonavir, an older medication widely used in combination treatments for HIV infection.
To date, Gilead Sciences Inc (NASDAQ:GILD)'s intravenous drug remdesivir is the only approved antiviral treatment for COVID-19 in the United States.
Pfizer has also started another study of PF-07321332 in non-hospitalized, symptomatic adult patients.
Merck and partner Ridgeback Biotherapeutics recently launched a late-stage trial of their experimental drug molnupiravir for prevention of the COVID-19 infection.
Molnupiravir is also being studied in a late-stage trial in non-hospitalized patients to see if it reduces the risk of hospitalization or death.