Pfizer says COVID-19 antiviral pill effective against omicron

Pfizer’s COVID-19 treatment pill Paxlovid appears to be effective against the omicron variant, the company announced Tuesday.

Pfizer said three separate lab studies showed nirmatrelvir, the drug’s main protease inhibitor, maintains its effectiveness against the omicron variant of the virus. A protease inhibitor is a class of drugs that stop a virus from replicating.

Patients take two tablets of nirmatrelvir with one tablet of another antiviral, called ritonavir, twice a day for five days.

Paxlovid is seen as a major step forward in the fight against the virus, with trials showing that it reduced the risk of hospitalization or death by 89 percent in high-risk patients. 

However, the emergence of the omicron variant has led to questions about the effectiveness of Paxlovid, as well as other COVID-19 treatments, because the variant has many more mutations compared to earlier strains.

Pfizer announced the findings in a press release and said it was submitting them to pre-print medical journals. 

“These data suggest that our oral COVID-19 therapy can be an important and effective tool in our continued battle against this devastating virus and current variants of concern, including the highly transmissible Omicron,” said Mikael Dolsten, Pfizer’s chief scientific officer. “We will continue to monitor the treatment’s activity in real-world settings and believe that these in vitro findings will continue to be validated.”

The Food and Drug Administration last month authorized Paxlovid for use in high-risk patients. The fact that Paxlovid is a pill rather than an injection, as in previous treatments, is expected to make it more accessible and easier to take. 

But the treatment is intended to be started within five days of the onset of symptoms, which could pose a challenge. Plentiful testing will be needed to ensure that people know that they have COVID-19 and can get those results in time to be able to seek the treatment.

Supply of Paxlovid is also constrained due to the time it takes to manufacture, and the U.S. has distributed fewer than 200,000 treatment courses so far.