ABSTRACT
A 54-year-old woman presented to our hospital with a fever and cough. The patient had a medical history of follicular lymphoma treated with obinutuzumab. She was infected with an omicron variant of coronavirus disease 2019 and developed viral pneumonia. Antibiotics, molnupiravir, sotrovimab, and prednisolone were administered but were ineffective. The patient's symptoms and pneumonia persisted. She could not produce antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) because she was administered obinutuzumab. Finally, when we administered 300 mg of tixagevimab and cilgavimab, pneumonia immediately improved. However, the infection was prolonged for more than 4 months. Patients treated with anti-CD20 monoclonal antibodies may have a prolonged SARS-CoV-2 infection. In such cases, tixagevimab/cilgavimab may be effective.