A study of Pfizer’s new COVID pill Paxlovid confirmed that the antiviral medication helps prevent severe disease in high-risk individuals sick with the virus, NBC News reports.

Pfizer announced on Tuesday that the oral pill prevents the coronavirus from replicating itself within the body, and was shown to work best when taken three days after symptoms begin. Pfizer also added that laboratory studies have so far shown Paxlovid to be effective against the Omicron variant, which has been surging in South Africa and Europe since its discovery on Nov. 24. According to Pfizer, the drug seems to attack one of Omicron’s key proteins, known as a protease, just as efficiently as in other variants.

“We are confident that, if authorized or approved, this potential treatment could be a critical tool to help quell the pandemic,” Albert Bourla, Pfizer’s chief executive, said in a statement.

Pfizer added that the pill reduced the risk of hospitalization and death by 89 percent if given within three days of experiencing symptoms. If given within five days, the pill still quelled the risk by 88 percent.

The company asked the Food And Drug Administration to authorize the pill last month based on preliminary data, and the new study, based on an analysis of 2,246 high-risk unvaccinated volunteers, matched up with that initial data. The results have reportedly strengthened Pfizer’s request for approval, meaning Americans could potentially have access to the pill by year’s end.

A full course of the treatment is three pills, taken twice daily for five days, Pfizer said. The treatment combines a new antiviral drug named nirmatrelvir and an older HIV medication called ritonavir. And while the regiment did cause side effects, the company said they were mostly mild but didn’t elaborate further.

The announcement comes as Pfizer’s competitor, Merck, awaits authorization for its own COVID pill called molnupiravir. In October, Merck announced with its partner Ridgeback Biotherapeutics that the pill reduced a high-risk individual’s chances of hospitalization and death by 50 percent when taken within five days of showing symptoms. Advisory committee members initially expressed concern about the drug's safety and noted potential risks to pregnant women and their fetuses.

Dr. Mikael Dolsten, the chief scientific officer of Pfizer,  said that Pfizer would have 180,000 courses of treatment ready once Paxlovid was authorized. He added that the company aimed to make 80 million courses available around the world in 2022.