The global pandemic of coronavirus disease 2019 (COVID-19) is still ongoing, with the emergence of new dominant variants. Japan is no exception, with numerous cases reported nationwide. These data highlight the urgent need for developing effective therapeutic options, particularly for early treatment of patients with risk factors for severe COVID-19 Previous studies have demonstrated the efficacy and safety of ensitrelvir, an antiviral agent, in patients with mild to moderate COVID-19, regardless of the presence of risk factors.

In the present randomized controlled trial, we conducted a head-to-head comparison of viral load reduction between patients treated with ensitrelvir, whose effectiveness in patients with risk factors has not yet been established, and molnupiravir, an antiviral agent with anticipated clinical benefits in such patients, in order to evaluate the superiority of ensitrelvir in patients with risk factors for severe disease. The primary endpoint was the change from baseline of the SARS-CoV-2 RNA levels on Day 4 (with Day 1 defined as the first day of the trial drug administration).

A total of 150 patients (75 per group) were enrolled between May 2023 and August 2023. Our findings showed no significant difference in the virological efficacy in patients with risk factors for severe COVID-19 treated with ensitrelvir or molnupiravir. Furthermore, no new safety concerns were identified.

These results suggest that ensitrelvir may serve as a valid treatment option for patients with risk factors for severe COVID-19.

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.