Real-world effectiveness of nirmatrelvir-ritonavir and molnupiravir in non-hospitalized adults with COVID-19: a population-based, retrospective cohort study
Anselm Jorda, Dominik Ensle, Hubert Eser, Florentin Glötzl, Benjamin Riedl, Marton Széll, Arschang Valipour, Alexander Zoufaly, Christoph Wenisch, Doris Haider, Heinz Burgmann, Florian Thalhammer, Florian Götzinger, Bernd Jilma, Robin Ristl, Ursula Karnthaler, Markus Zeitlinger
Abstract
OBJECTIVES: The real-world effectiveness of the oral antivirals nirmatrelvir-ritonavir and molnupiravir against the SARS-CoV-2 Omicron variant remains uncertain. We aimed to estimate their effectiveness in non-hospitalized adults with COVID-19. METHODS: This retrospective cohort study used data from the Municipal Department for Public Health Services of Vienna, Austria, to identify non-hospitalized adults with confirmed SARS-CoV-2 infection between January 2022 and May 2023. Nirmatrelvir-ritonavir users were compared with untreated controls and molnupiravir users with untreated controls by calculating adjusted risk differences (aRDs) using a covariate-adjusted logistic regression model with inverse probability weighting. Outcomes were hospitalization and all-cause death within 28 days. RESULTS: We identified 113 399 eligible cases (90 481 untreated controls, 12 166 nirmatrelvir-ritonavir users, and 10 752 molnupiravir users). Over 96% of the patients were immunized by previous infection or vaccination. In the nirmatrelvir-ritonavir analysis, the estimated risk of hospitalization was 0.57% (95% CI, 0.35-0.78) in nirmatrelvir-ritonavir users and 1.09% (95% CI, 0.86-1.32) in untreated controls (aRD, -0.53%; 95% CI, -0.77 to -0.28). The estimated risk of death was 0.0% (95% CI, 0.0-0.0) in nirmatrelvir-ritonavir users and 0.13% (95% CI, 0.08-0.18) in untreated controls (aRD, -0.13%, 95% CI, -0.18 to -0.08). The number needed to treat to prevent hospitalization and death was 190 (95% CI, 130-356) and 792 (95% CI, 571-1289), respectively. These statistically significant aRDs were restricted to the subgroup of patients ≥60 years. In the molnupiravir analysis, the estimated risk of hospitalization was 1.36% (95% CI, 0.95-1.77) in molnupiravir users and 1.16% (95% CI, 0.93-1.39) in untreated controls (aRD, 0.2%; 95% CI, -0.08 to 0.49). The estimated risk of death was 0.12% (95% CI, 0.01-0.23) in molnupiravir users and 0.14% (95% CI, 0.06-0.21) in untreated controls (aRD, -0.01%; 95% CI, -0.08 to -0.06). DISCUSSION: Among outpatients aged ≥60 years with COVID-19 in an Omicron-dominated era, treatment with nirmatrelvir-ritonavir was associated with a lower risk of hospitalization and all-cause death within 28 days, albeit with wide CIs and high numbers needed to treat. This finding was not observed in molnupiravir users and younger nirmatrelvir-ritonavir users.