Pfizer (NYSE:PFE) today announced that its oral antiviral cut the risk of hospitalization or death by 89% in an interim analysis of the Phase 2/3 EPIC-HR trial.

Until recently, there were no oral treatments against the novel coronavirus. Molnupiravir, an oral antiviral from Merck (NYSE:MRK) and Ridgeback Biotherapeutics, recently won approval in the United Kingdom and is poised to find use in other countries. Merck said molnupiravir led to an approximately 50% reduction in hospitalizations and deaths versus placebo.

The Pfizer EPIC-HR trial study found that 7% of the participants who received a placebo were later hospitalized or died. However, only 0.8% of patients who received Paxlovid were hospitalized within 28 days, and there were no deaths in the drug group.

The trial results “suggest that our oral antiviral candidate, if approved or authorized by regulatory authorities, has the potential to save patients’ lives, reduce the severity of COVID-19 infections, and eliminate up to nine out of ten hospitalizations,” Pfizer CEO Albert Bourla said in a news release.

Pfizer will stop enrollment in the study based on feedback from the independent Data Monitoring Committee and FDA. The company plans to file data from the trial with the FDA as part of its request for emergency use authorization.

In addition to its protection against serious COVID-19 infections, the drug appeared to be well tolerated. Some 19% of Paxlovid recipients had adverse events, lower than the 21% of placebo recipients did. The majority of the events were mild.

Paxlovid is a SARS-CoV-2-3CL protease inhibitor, while molnupiravir is a ribonucleoside analog.

PFE shares jumped 10.86% to $48.61, an all-time high for the stock. Meanwhile, MRK shares fell 9.86% to $81.61.