Pfizer Inc. announced Friday that its pill to treat novel COVID-19 was found to reduce the risk of hospitalization or death by 89% among high-risk adult patients in a clinical trial.

The vaccine-maker said there had been no deaths reported in patients who had received Paxlovid along with another antiviral through day 28 of the study, whereas 10 deaths were reported in patients who had received a placebo.

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Similar reductions in COVID-19-related hospitalization or death were observed in patients – who were unvaccinated with mild to moderate symptoms – treated within five days of symptom onset.

Few details were reported on side effects but Pfizer said rates of problems were similar between the two groups at about 20%.

In this Nov. 9, 2020, file photo, pedestrians walk past Pfizer world headquarters in New York. (AP Photo/Bebeto Matthews, File)

Additionally, the company said at the recommendation of an independent data monitoring committee and in consultation with the U.S. Food and Drug Administration (FDA), it would cease further enrollment into the study due to "the overwhelming efficacy demonstrated" in the results. 

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Pfizer plans to submit the data to the FDA for emergency use authorization (EUA) as soon as possible.

"These data 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 statement.

Pfizer's is the second pill to show effectiveness against COVID-19 and the first specifically designed to attack the virus.

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A similar pill from Pfizer competitor Merck is under FDA review and was cleared by U.K. regulators Thursday.

Currently, all COVID-19 treatments used in the U.S. require an IV or injection.

The Associated Press contributed to this report