Safety of Nirmatrelvir-Ritonavir Administration in Children With Immunodeficiency and/or Comorbidities With SARS-CoV-2 Infection: A Retrospective Clinical Report.

Introduction: Despite the generally mild course of COVID-19 in children, immunocompromised patients may experience complications or severe infection. This study reports the clinical outcomes of pediatric patients treated with nirmatrelvir and ritonavir (N/R) for SARS-CoV-2 infection.

Methods: We retrospectively reported the data of children with any immunodeficiency with COVID-19 who received N/R treatment between March 2022 and June 2023 at the Bambino Gesù Children's Hospital. Patients were treated with N/R for 5 days. We compared liver and kidney function before and after treatment with N/R and looked for a relationship between the duration of COVID-19 infection and the time from positivity to administration of N/R administration.

Results: A total of 85 pediatric immunocompromised patients with COVID-19 were included in the study, with a mean age of 10.7 years (SD 4.8), mostly males (60%). We found a significant difference in the viral load before and after N/R administration. Four patients (4.7%) experienced adverse events related to N/R therapy. One of these had to discontinue N/R administration. Three patients (3.5%) experienced negative effects of drug interactions during N/R therapy, namely an increase of sirolimus and ciclosporin serum levels. A significant positive correlation was found between the time from SARS-CoV-2 positivity to N/R administration and the duration of SARS-CoV-2 swab positivity (R = 0.78, P < 0.001), suggesting that the earlier N/R is administered, the shorter the duration of COVID-19 in the study sample.

Conclusion: Our experience shows that N/R is reasonably safe in the pediatric population and could favor viral clearance, thus reducing the duration of infection.