Application of nirmatrelvir/ritonavir for the treatment of severe COVID-19 in a 3-year-old child.

Introduction: Nirmatrelvir/ritonavir (Paxlovid) is an effective antiviral drug for treating coronavirus disease 2019 (COVID-19) in adults. However, Paxlovid treatment of children, especially those who are under 12 years and with severe underlying diseases, is rare.

Case report: A three-year-old COVID-19 patient (weighing 14.5 kg) was infected by the Omicron variant (BA.5.2) after undergoing allogeneic hematopoietic stem cell transplantation. The patient had severe bilateral pneumonia along with recurrent fever. The patient was administered 150 mg of nirmatrelvir plus 50 mg of ritonavir twice daily for 5 days, starting 27 days after the initial severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) positive test. Clinical manifestations and chest computed tomography improved considerably after the treatment. The real time reverse transcriptase polymerase chain reaction (RT-PCR) cycle threshold values increased from 23.92 to 38.40 in the case of ORF 1-ab gene, and from 22.22 to 36.28 in the case of N gene. Only a mild increase in serum urea nitrogen (10.10 mmol/L), alanine transaminase (ALT, 65 IU/L), and aspartate transaminase (AST, 68.5 IU/L) was observed.

Conclusions: Paxlovid can effectively inhibit the replication of SARS-CoV-2 and help in improving the clinical manifestations in pediatric COVID-19 patients. Our study provided novel information on Paxlovid treatment in very young children.