Successful 30-Day Nirmatrelvir/Ritonavir Treatment of a Patient Who Developed Multi-relapsed COVID-19 After Receiving R-CHOP Against Follicular Lymphoma.

A 58-year-old male developed three coronavirus disease 2019 (COVID-19) relapses within three months after rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) chemoimmunotherapy against relapsed follicular lymphoma. Five- and 10-day remdesivir courses failed to achieve viral clearance. A 30-day nirmatrelvir/ritonavir course provided symptom resolution and sustained reverse transcription and quantitative polymerase chain reaction (RT-qPCR) negativity. Genome analyses identified cultured live virus (day 59) and nasopharyngeal-swab viral RNA (days 74, 82, 95) as Omicron BA.5 sublineage BF.13. Normal immunoglobulin (Ig)G levels and high neutralizing activities against BA.5 were maintained throughout the infection's course. Extended nirmatrelvir/ritonavir antiviral treatment may be effective for patients administered anti-CD20 therapy who develop prolonged/relapsed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection despite possessing high neutralizing activities.