新型コロナウイルス感染症（COVID-19）は，主流となる株の変異を繰り返しながら，世界的流行が継続している．わが国も例外ではなく多くの患者が報告されていることから，現時点においても有効な治療法が求められ，特に重症化リスク因子を持つ患者の早期治療が必要とされている．エンシトレルビルは，先行試験において重症化リスク因子の有無にかかわらず軽症・中等症患者に対する有効性と安全性が検証された抗ウイルス薬である．一方で，重症化リスク因子を有するCOVID-19患者に対するエンシトレルビルの有効性の検証は十分ではなかった．

今回，エンシトレルビルと，重症化リスク因子を有する患者に対する有効性が期待できるとされるモルヌピラビルを直接比較し，エンシトレルビルのモルヌピラビルに対する優越性を検証した．主要評価項目はDay 4（投与開始日をDay 1と定義）のSARS-CoV-2ウイルスRNA量のベースラインからの変化量とした．

2023年5月から2023年8月の期間に登録された150例（各群75例）を対象に検討した結果，エンシトレルビルは重症化リスク因子を有する患者群においてもモルヌピラビルとウイルス学的有効性に有意な差がなく，安全性については新たな懸念はないことが示された．

以上から，エンシトレルビルは重症化リスク因子を有するCOVID-19患者の治療選択肢の一つになると考えられた．

Human immunodeficiency virus (HIV) causes immunodeficiency by infecting and destroying CD4-positive T cells. However, HIV infection has also been reported to manifest with rheumatic-like symptoms, making differential diagnosis from rheumatic diseases important in clinical practice. In this report, we present two cases in which HIV infection was identified after an initial diagnosis of a rheumatic disease. Case 1: The patient was initially diagnosed as having Behçet's disease based on a history of recurrent oral ulcers and HLA-B51 positivity, but subsequently developed recurrent diarrhea episodes and gastrointestinal ulcers. Further investigation revealed the diagnosis of HIV infection. Case 2: The patient was diagnosed as having systemic lupus erythematosus based on the presence of facial erythema, cytopenias, and seropositivity for antinuclear and anti-double-stranded DNA antibodies. He subsequently developed fever and weight loss, and further examination led to the diagnosis of HIV infection. In both cases, clinical improvement was achieved with antiretroviral therapy and treatment of concomitant infections. These cases highlight the importance of recognizing that HIV infection can mimic rheumatic diseases. HIV screening should be considered in cases where clinical features are atypical or there is insufficient response to conventional treatments.

A woman in her 40s with a history of cough and fever was admitted to our hospital with hypoxia and bilateral infiltrative opacities on the chest radiograph. Diagnostic tests on upper respiratory tract and endobronchial sputum specimens were positive for human metapneumovirus (hMPV). Although worsening hypoxia warranted endotracheal intubation on day 2, the patient gradually improved with supportive treatment. On day 9, the endobronchial sputum specimens turned negative for hMPV. Thereafter, after the patient was weaned from the respirator, the respiratory failure worsened again, and she developed takotsubo cardiomyopathy as a complication. With continued supportive care, however, the respiratory failure and takotsubo cardiomyopathy resolved, and the patient was discharged on day 36. We have illustrated the detailed clinical course of severe hMPV-related pneumonia complicated by takotsubo cardiomyopathy in our patient, which we believe would be informative for physicians managing hMPV infection.