Use of nirmatrelvir and serious consequences of Covid-19 during the surge of Omicron
The oral protease inhibitor nirmatrelvir has shown substantial efficacy in high-risk unvaccinated patients infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variant B.1.617.2 (delta). ). Data regarding the effectiveness of nirmatrelvir in preventing severe outcomes of coronavirus disease 2019 (Covid-19) variant B.1.1.529 (omicron) are limited.
We obtained data for all members of Clalit Health Services who were 40 years of age or older at the start of the study period and who were assessed as eligible to receive nirmatrelvir treatment during the omicron surge. A Cox proportional hazards regression model with time-dependent covariates was used to estimate the association of nirmatrelvir treatment with hospitalization and death due to Covid-19, with adjustment for sociodemographic factors, coexisting conditions and previous immune status against SARS-CoV-2.
A total of 109,254 patients met the eligibility criteria, of whom 3,902 (4%) received nirmatrelvir during the study period. Among patients aged 65 or older, the rate of hospitalizations due to Covid-19 was 14.7 cases per 100,000 person-days in treated patients compared to 58.9 cases per 100,000 person-days in untreated patients. treated (adjusted hazard ratio, 0.27; 95% confidence interval [CI], 0.15 to 0.49). The adjusted hazard ratio for death from Covid-19 was 0.21 (95% CI, 0.05 to 0.82). Among patients aged 40 to 64, the rate of hospitalizations due to Covid-19 was 15.2 cases per 100,000 person-days in treated patients and 15.8 cases per 100,000 person-days in untreated patients (adjusted hazard ratio, 0.74; 95% CI, 0.35 to 1.58). The adjusted hazard ratio for death from Covid-19 was 1.32 (95% CI, 0.16 to 10.75).
Among patients 65 or older, rates of hospitalization and death from Covid-19 were significantly lower in those who received nirmatrelvir than in those who did not. No evidence of benefit was found in young adults.