The U.S. Food and Drug Administration on Thursday granted full approval to Pfizer's oral antiviral COVID-19 treatment, Paxlovid, for adults at high risk of progression to severe disease.

The approval for the pill, initially authorized in late 2021 for emergency use in the U.S., will provide doctors with more flexibility in prescribing it to adults with severe COVID-19 symptoms.

"Today's approval demonstrates that Paxlovid has met the agency's rigorous standards for safety and effectiveness, and that it remains an important treatment option for people at high risk for progression to severe COVID-19," FDA's Patrizia Cavazzoni said in a statement.

The decision comes more than two months after a panel of advisers to the health regulator voted in favor of granting full approval for the drug.

Data presented by both the FDA and Pfizer during the advisory meeting helped ease safety concerns around a potential rebound in COVID-19 symptoms after a five-day Paxlovid course.

The concerns emerged after numerous anecdotal reports about a return of symptoms following treatment with Paxlovid, including in high-profile patients such as President Joe Biden and Dr. Anthony Fauci.