Drugmaker Pfizer announced Tuesday that its COVID-19 pill is highly effective at preventing severe illness and death, and also noted that it’s effective against the newly discovered omicron variant — though further studies are needed.

Pfizer said Tuesday that the pill, known as Paxlovid, is 89% effective at reducing the risk of hospitalization or death if given within three days of onset symptoms, and 88% if given within five days.

"This news provides further corroboration that our oral antiviral candidate, if authorized or approved, could have a meaningful impact on the lives of many, as the data further support the efficacy of PAXLOVID in reducing hospitalization and death and show a substantial decrease in viral load," Pfizer CEO Albert Bourla said in a statement. “This underscores the treatment candidate’s potential to save the lives of patients around the world.

"Emerging variants of concern, like Omicron, have exacerbated the need for accessible treatment options for those who contract the virus, and we are confident that, if authorized or approved, this potential treatment could be a critical tool to help quell the pandemic," Bourla added.

The results were based on a clinical trial that included 2,246 adults. The efficacy rate for the three-day timeframe was consistent with the interim analysis Pfizer announced last month, but the 88% effectiveness for the five-day window was 85% higher than in the earlier findings.

Pfizer said just 0.7% of trial participants who were treated with the drug were hospitalized, compared to 6.5% in the placebo group. There were no deaths reported in the Paxlovid group, but 12 in the placebo group.

The pill is also 94% effective in patients 65 years or older, one of the populations at highest risk for hospitalization or death, Pfizer said.

The rate of side effects was comparable between the Paxlovid and placebo groups, and most were mild, the company said.

Paxlovid is designed to block the activity of an enzyme the coronavirus needs to replicate.

Pfizer announced last month that it has applied for emergency use authorization from the Food and Drug Administration for the pill. 

In a statement, President Joe Biden said he is "encouraged" by the data released by Pfizer, saying it "provides another potentially powerful tool in our fight against the virus, including the Omicron variant."

"Getting vaccinated and getting your booster shot remain the most important tools we have to save lives. But if this treatment is indeed authorized — and once the pills are widely available — it will mark a significant step forward in our path out of the pandemic," Biden continued. "The combination of widespread vaccinations and boosters, testing, and effective pills for those who become ill will help us further reduce the impact of COVID-19 on our lives and our economy as we continue to build back better."

Paxlovid is one of two COVID-19 pills that could soon hit the market. An FDA advisory panel narrowly voted, 13-10, last month to recommend a drug developed by Merck and Ridgeback Biotherapeutics, but the FDA itself has yet to make a decision. That pill, molnupiravir, was found to be 30% effective at preventing hospitalization or death. Some members of the advisory committee expressed concerns about the possibility of birth defects if molnupiravir is used during pregnancy.

Pfizer says it can make about 80 million courses of Paxlovid by the end of 2022. The federal government has secured 10 million courses of Pfizer’s drug and 3.1 million of Merck’s.

"Several steps remain before the Pfizer pill can become available, including authorization by the Food and Drug Administration," Biden said. "To make sure that we are ready, my Administration has already placed an order for enough of these pills to treat 10 million Americans."