Objective:

To perform an updated meta-analysis of cohort studies comparing outpatients treated with Nirmatrelvir-Ritonavir (N-R) with untreated patients during the omicron phase of the pandemic, specifically from December 2021 onwards.

Key Findings:

• N-R showed a relative risk for hospitalization or death of 0.62 (95% CI 0.55 to 0.70) in previous studies, with hospitalization rates in untreated patients determined from various published reports.
• Hospitalization rates in untreated patients decreased over time, affecting the absolute risk reduction for N-R, which may require further elaboration.

Interpretation:

The efficacy of N-R may be influenced by the changing epidemiological landscape, including lower hospitalization rates due to vaccination and prior infections, which should be detailed further.

Limitations:

• Only published studies were included, potentially missing relevant data.
• Exclusion of studies with special populations may limit generalizability.
• Potential biases in the included studies could affect the results.

Conclusion:

N-R remains effective in reducing hospitalization and mortality in outpatients during the omicron phase, but the absolute benefits may be lower than in earlier phases of the pandemic.