Nirmatrelvir-Ritonavir and Viral Load Rebound in Covid-19. 9/7/22. Anderson AS. N Engl J Med.

Using data from the EPIC-HR3 trial which compared nirmatrelvir-ritonavir to placebo in unvaccinated patients, the authors found that viral load rebound following nirmatrelvir-ritonavir is not retrospectively associated with low nirmatrelvir exposure, recurrence of moderate to severe symptoms or development of resistance to nirmatrelvir. During the recruitment period from June to December 2021 which coincided with delta variant predominance, viral load rebound occurred in 23 of 990 patients (2.3%) in the nirmatrelvir– ritonavir group and in 17 of 980 (1.7%) in the placebo group. These results – published in a research letter – suggest that viral load rebound may be a natural feature of SARS CoV-2 infections. However, viral load as determined by PCR assay does not translate directly to the presence of current or new clinical syndrome.

https://www.nejm.org/doi/10.1056/NEJMc2205944