Nirmatrelvir in combination with ritonavir (Paxlovid) is recommended for the treatment of COVID-19 in high-risk groups. However, the efficacy for severe COVID-19 in patients who are fully vaccinated has not been clearly established.

Recently, a multicenter study funded by Pfizer examined the efficacy of Paxlovid in fully vaccinated patients (Hammond J, Fountaine RJ, Yunis C, et al. Nirmatrelvir for Vaccinated or Unvaccinated Adult Outpatients with Covid-19. N Engl J Med. 2024 Apr 3;390(13):1186-1195). The authors randomly assigned 1,296 patients to receive either Paxlovid or placebo every 12 hours for 5 days. The median time to sustained relief of symptoms was 12 days in the Paxlovid group and 13 days in the placebo group. Five participants (0.8%) in the Paxlovid group and 10 (1.6%) in the placebo group were hospitalized for COVID-19. This represented a 50% reduction in the incidence of severe disease.

The authors concluded, “The time to sustained alleviation of all signs and symptoms of Covid-19 did not differ significantly between participants who received nirmatrelvir-ritonavir and those who received placebo.” Several news outlets reported the results of this trial by concluding that Paxlovid didn’t work. But the goal of Paxlovid is to prevent high-risk patients who were or were not vaccinated from progressing to severe disease. Although the numbers of those with severe disease in this study were small, Paxlovid was beneficial.

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