The following is a summary of “Nirmatrelvir for Vaccinated or Unvaccinated Adult Outpatients with COVID-19,” published in the April 2024 issue of Infectious Disease by Hammond et al.
Researchers conducted a retrospective study to assess the effectiveness of nirmatrelvir-ritonavir in mild-to-moderate patients with COVID-19 at standard risk or fully vaccinated with at least one severe illness risk factor.
They conducted a phase 2–3 trial, randomly assigning adults with confirmed COVID-19 symptoms within the past 5 days to either nirmatrelvir–ritonavir or placebo every 12 hours for 5 days. Eligible participants included fully vaccinated individuals with at least one risk factor for severe disease and unvaccinated or partially vaccinated individuals with or without risk factors. Participants recorded COVID-19 signs and symptoms daily from day 1 to day 28. The primary goal was to determine the time until all targeted COVID-19 signs and symptoms were alleviated. COVID-19-related hospitalization and death from any cause were monitored until day 28
The results showed 1,296 participants who underwent randomization and 1,288 received at least one dose of nirmatrelvir–ritonavir (654 participants) or placebo (634 participants) and had at least one postbaseline visit. The median time to sustained alleviation of all targeted signs and symptoms of COVID-19 was 12 days in the nirmatrelvir–ritonavir group and 13 days in the placebo group (P=0.60). Five participants (0.8%) in the nirmatrelvir–ritonavir group and 10 (1.6%) in the placebo group were hospitalized for COVID-19 or died from any cause (difference, −0.8 % points; 95% CIl, −2.0 to 0.4). The percentages of participants with AEs were similar in the two groups (25.8% with nirmatrelvir–ritonavir and 24.1% with placebo). In the nirmatrelvir–ritonavir group, the most commonly reported treatment-related AEs were dysgeusia (in 5.8% of the participants) and diarrhea (in 2.1%).
Investigators concluded that nirmatrelvir-ritonavir did not significantly reduce the time to feeling better compared to a placebo in people with mild-to-moderate COVID-19.