Abstract
BACKGROUND: Immunocompromised individuals are infected with persistent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and often refractory to treatment. CASE SUMMARY: A 56-year-old woman undergoing chemotherapy for follicular lymphoma experienced relapsing pulmonary infiltrates and a consistently low cycle threshold value of nasal swab SARS-CoV-2 PCR over a 5-month period. Despite repeated remdesivir and glucocorticoid therapy, her respiratory symptoms worsened and progressed to respiratory failure. Viral genome analysis revealed that the variant strain at onset was XBB, whereas the strains repeatedly detected more than 2 months after onset were XBB.2.3. CONCLUSION: The genome analysis indicated that genomic mutations accumulate due to continuous XBB infection. The patient recovered after treatment with nirmatrelvir/ritonavir for 20 days.