Effectiveness and safety of molnupiravir in the intended-use population: an observational cohort study

Objectives: Previous research reported inconsistent results on the efficacy of molnupiravir in treating COVID-19. Moreover, efficacy was not assessed in the intended-use population (IUP), as defined by the FDA. Therefore, we aimed to evaluate the effectiveness and safety of molnupiravir for the treatment of COVID-19 in the IUP. Methods: We performed a retrospective cohort study on all IUP in Israel's Clalit Health Services from January 16, 2022, to February 16, 2023. The effectiveness outcome was the incidence of hospitalization or death due to COVID-19, and the safety outcome was the incidence of all-cause mortality within 35 days of SARS-CoV-2 infection. Cox-proportional hazard models were used to analyse the data after 1:5 propensity-score matching. Results: A total of 49 515 patients met the eligibility criteria. Of them, 3957 molnupiravir-treated patients were matched to 19 785 untreated patients. In molnupiravir-treated patients, 70 out of 3957 (5.1 per 10 000 person per day) experienced COVID-19-related hospitalization or death, compared with 699 out of 19 785 untreated patients (10.4 per 10 000 person per day); RR: 0.50 (95% CI, 0.39–0.64). All-cause mortality was also lower in the treated group, with 41 out of 3957 (3.0 per 10 000 person per day) experiencing mortality compared with 414 out of 19 785 untreated patients (6.1 per 10 000 person per day); RR: 0.50 (0.36–0.68). Discussion: In a real-world cohort of IUP, molnupiravir therapy was associated with a significant reduction in hospitalizations or deaths due to COVID-19 and all-cause mortality.