Respiratory syncytial virus (RSV) is commonly known as a pathogen of the bronchiolitis in children, however, recently also as a pathogen of the severe virus pneumonia in adults, especially elderly persons, and vaccines for elderly persons have been developed. There are two vaccines, such as the vaccines targeted for subgroup A with the adjuvant, and that targeted for both subgroup A and B but not included the adjuvant in Japan. Both vaccines are considered effective to prevent not only the incident of RSV infection/pneumonia, but also the exacerbations of the elderly persons with underlying diseases including chronic cardiopulmonary diseases.

Respiratory virus co-infections have been suggested to happen frequently and exacerbate patients’ conditions, but little is known about the detailed rates and the combinations of viruses during the COVID-19 pandemic period. A total of 255 symptomatic patients who underwent multiplex PCR tests were analyzed, and it was found that 6 (6/255=2.4%) patients were infected with multiple viruses. The patients ranged in age from 1 to 38 years, and one female patient was pregnant. Of the 6 patients, 4 had fever, and 5 had human rhinovirus/enterovirus and another virus. These data suggested that the rate of respiratory virus co-infection was low, and the combination of SAS-CoV-2 and other viruses was rare even during the COVID-19 pandemic.

Baloxavir marboxil (BXM) is a novel anti-influenza agent that developed in Japan and inhibit the cap endonuclease specifically, and suggested the more clinical effectiveness in influenza. BXM reduces viral shedding more than do neuraminidase inhibitors (NAIs), and its clinical efficacy is equivalent to that of NAIs but is superior to that of NAIs in the case of type B influenza. BXM does not demonstrate any issues with safety, and treatment with BXM reduces the incidences of complicating sinusitis and bronchitis. Prophylactic administration of BXM inhibits intrafamilial transmission of influenza although low susceptible viruses with a PA/I38X substitution are isolated with a certain frequency following administration of BXM. Finally, In influenza treatment for patients aged 12−19 years and for adult outpatients, BXM can be used with the same recommendation level as oseltamivir.

Background: The titers of SARS-COV-2 antigens are frequently used as markers of viral activity and threshold for release from quarantine and treatment. COVID-19 patients were treated with several antiviral agents, including remdesivir (RDV) and ensitrelvir (ESV), which is a novel anti-SARS-CoV-2 agent recently suggested to have strong antiviral activity. Cases: We present the cases of two patients whose SARS-CoV-2 antigens were successfully decreased by oral administration of ESV after they could not be decreased by RDV drip infusion. Case 1 was a 74-year-old man who was admitted with SARS-CoV-2 infection and had been infected by the virus a month earlier and relapsed twice. He had been treated with rituximab for diffuse B cell lymphoma and not received vaccination for SARS-CoV-2. RDV was administered intravenously two weeks earlier and again 4 days earlier, but it failed to control the infection, and he was transferred to our hospital (day 1). Intravenous RDV was restarted on day 1, but viral antigens remained high until day 5. The RDV was then switched to oral ESV, and viral antigen titers were successfully decreased on days 8, 10, and 12. Case 2 was an 81-year-old man who was admitted with SARS-CoV-2 infection on day 0. He had heart failure and diabetes mellitus, and had not received vaccination for SARS-CoV-2. Intravenous RDV was started on day 1, but viral antigens were still high until day 8. He was then switched from RDV to oral ESV, and viral antigen titers were successfully decreased on day 11. Conclusions: These cases suggest that ESV might be more effective than RDV for reducing viral activity, and it is easy to administer orally.