The SARS-CoV-2 infection rebound among patients receiving antiviral agents, convalescent plasma, or no treatment: a systematic review with meta-analysis

Abstract

Background - There is some evidence showing rebound of COVID-19 infections in patients treated with nirmatrelvir-ritonavir between 2 and 8 days following cessation of the antiviral treatment. COVID-19 rebound is not unique to patients treated with nirmatrelvir-ritonavir, but is also observed in molnupiravir recipients, in patients who did not receive any antiviral treatment and in patients who received convalescent plasma (CP).

Materials and methods - This was a systematic review with meta-analysis of clinical trials evaluating rates of virologic and clinical rebound in COVID-19 patients receiving antiviral agents, CP or no treatment. Both randomized clinical trials and controlled cohort studies were considered. The methodological quality of trials was assessed using ROB-2 and ROBIN-1 checklists, and the GRADE approach.

Results - Data were available from 16 trials. The occurrence of virologic rebound was more commonly observed among nirmatrelvir recipients than among untreated patients (relative risk [RR]=2.12; 95% confidence interval [CI]: 1.38-3.28; p=0.0007). No differences were observed in the occurrence of virologic rebound between nirmatrelvir-ritonavir and molnupiravir recipients (RR=1.01; 95% CI: 0.71-1.43). Similar rates of virologic rebounds were observed in molnupiravir recipients and untreated patients (RR=1.14; 95% CI: 0.81-1.6). One study in the pre-omicron period compared rates of virologic rebound between patients receiving standard of care with or without CP: no differences were observed between groups (RR=1.04; 95% CI: 0.55-1.99). Rates of clinical rebound were reported in seven trials, five evaluating nirmatrelvir-ritonavir and untreated patients, and two evaluating nirmatrelvir-ritonavir and molnupiravir recipients. No statistically significant differences between groups were observed. For all these comparisons, the certainty of the available evidence was graded as low or moderate.

Discussion - Virologic rebound of COVID-19 infections appears to be mild and self-limited, and was observed more commonly in nirmatrelvir-ritonavir recipients than in untreated patients, but was also observed in patients treated with molnupiravir or CP.