Abstract
A 68-year-old woman with follicular lymphoma was treated with chemotherapy, including the anti-CD20 monoclonal antibody obinutuzumab, and achieved remission. A month after the administration of obinutuzumab, the patient contracted coronavirus disease 2019 (COVID-19), and various antiviral drugs were administered. However, the infection had not been eliminated. One year and three months after chemotherapy, peripheral B cell recovery was achieved, and the infection had resolved. This report provides insight into the course of COVID-19 in patients with impaired humoral immunity.