Oral Nirmatrelvir and Ritonavir in Non-hospitalized Vaccinated Patients with Covid-19

Background Treatment of coronavirus disease-2019 (Covid-19) with nirmatrelvir plus ritonavir (NMV-r) in high-risk non-hospitalized unvaccinated patients reduced the risk of progression to severe disease. However, the potential benefits of NMV-r among vaccinated patients are unclear. Methods We conducted a comparative retrospective cohort study using the TriNetX research network. Patients ≥18 years of age who were vaccinated and subsequently developed Covid-19 between December 1, 2021, and April 18, 2022, were included. Cohorts were developed based on the use of NMV-r within five days of diagnosis. The primary composite outcome was all-cause emergency room (ER) visit, hospitalization, or death at a 30-days follow-up. Secondary outcomes included individual components of primary outcomes, multisystem symptoms, Covid-19 associated complications, and diagnostic test utilization. Results After propensity score matching, 1,130 patients remained in each cohort. A primary composite outcome of all-cause ER visits, hospitalization, or death in 30 days occurred in 89 (7.87%) patients in the NMV-r cohort as compared to 163 (14.4%) patients in the non-NMV-r cohort (OR 0.5, CI 0.39-0.67; p<0.005) consistent with 45% relative risk reduction. A significant reduction in multisystem symptom burden and subsequent complications such as lower respiratory tract infection, cardiac arrhythmia, and diagnostic radiology testing were noted in NMV-r treated patients. There was no apparent increase serious complications between days 10 to 30. Conclusion Treatment with NMV-r in non-hospitalized vaccinated patients with Covid-19 was associated with a reduced likelihood of emergency room visits, hospitalization, or death. Complications and overall resource utilization were also decreased.