Paxlovid Is Now Less Effective Against Covid, Study Shows

  • Pfizer drug still an important tool for high-risk patients
  • Performance of Merck drug better than in earlier trials

The pill was just 37% effective at preventing hospitalization or death in high-risk patients when compared to no Covid treatment at all, according to the study.

Photographer: Kobi Wolf/Bloomberg
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In a real-world study of people with Covid-19, Pfizer Inc.’s antiviral Paxlovid was less effective at preventing the infection’s most serious cases than it was in initial trials.

The pill was just 37% effective at preventing hospitalization or death in high-risk patients when compared to no Covid treatment at all, according to an observational study published Thursday in JAMA Network Open. In earlier studies, it cut the risk of hospitalization or death by as much as 89%.