Antiviral pill cuts COVID-19 hospitalizations and deaths by 89%, Pfizer says

(Image credit: Shutterstock)

A new COVID-19 pill cuts the risk of hospitalization or death by 89% when taken within three days of symptom onset, Pfizer recently announced. 

The antiviral pill, PAXLOVID, was given in a placebo-controlled clinical trial to people with COVID-19 who were at high risk of developing severe disease. The pill works by inhibiting an enzyme called a protease, which the virus SARS-CoV-2 needs to keep replicating. 

The drug was so clearly effective that an independent data monitoring committee recommended the trial be stopped so that people in the placebo-arm of the trial could receive the drug. Pfizer plans to submit the data to the Food and Drug Administration (FDA) for emergency use authorization "as soon as possible," according to a statement from the company.

Related: 14 coronavirus myths busted by science

More than 1,200 adults in the U.S. and abroad who tested positive for SARS-CoV-2 and had mild to moderate symptoms were enrolled in the clinical trial.  Participants had at least one underlying condition or characteristic that made them at high risk of developing severe disease. None of the participants were vaccinated, according to The New York Times.  Each participant took either PAXLOVID, in combination with ritonavir (an HIV drug that Pfizer says helps slow the breakdown of the antiviral drug, allowing it to stay in the body for longer), or a placebo pill every 12 hours for five days. 

Out of 389 participants who took PAXLOVID within three days of symptom onset, only three were hospitalized and none died, while out of 385 people who took the placebo within three days, 37 were hospitalized and seven died.

What's more, out of 607 participants who took PAXLOVID within five days of symptom onset (including the people who took the drug within three days), six were hospitalized and none died. Out of 612 who took the placebo within five days of symptom onset, 41 were hospitalized and 10 died. Adverse events were similar between the placebo and the experimental drug groups and most were mild, according to the statement. 

This isn't the first COVID-19 pill to be developed; The FDA is currently reviewing Merck's COVID-19 pill, known as molnupiravir, which the company said cut COVID-19 hospitalizations and deaths by 50% if taken within five days, and which was just approved in the United Kingdom, according to The Associated Press.

PAXLOVID is a modified version of a decades-old drug that was first developed as an intravenous therapeutic during the SARS epidemic, but that now specifically targets SARS-CoV-2 and can be taken as a pill, according to the Times. 

Originally published on Live Science.

Yasemin Saplakoglu
Staff Writer

Yasemin is a staff writer at Live Science, covering health, neuroscience and biology. Her work has appeared in Scientific American, Science and the San Jose Mercury News. She has a bachelor's degree in biomedical engineering from the University of Connecticut and a graduate certificate in science communication from the University of California, Santa Cruz.