Reduced Prescription of Baloxavir After Suspected Prevalence of a Baloxavir-Resistant Influenza Virus Strain and the Emergence of SARS-CoV-2 in a Tertiary Hospital in Japan

OBJECTIVE: The use of baloxavir, a new anti-influenza agent, began in Japan from the 2018 to 2019 season and became the focus of attention due to its efficient viral reduction ability; therefore, we should know the prescription changes of anti-influenza agents. METHODS: We analyzed the changes in the prescription of anti-influenza agents between the 2018–19 season and the 2019–20 season in our hospital. RESULTS: The share of baloxavir was 15%, while the shares of oseltamivir and laninamivir were 42% and 31%, respectively in the 2018–2019 season. However, in the 2019–20 season, the share of baloxavir and laninamivir was reduced to 3% and 17%, respectively, in contrast to an increase in the share of oseltamivir (66%). The total prescription of anti-influenza agents for patients decreased in the 2019–20 season (205 patients), compared with the 2018–19 season (509 patients). CONCLUSION: These results suggest significant changes such as a reduction in the prescription of anti-influenza agents, especially baloxavir, likely due to the suspected prevalence of a baloxavir-resistant strain of influenza virus and the emergence of SARS-CoV-2 in Japan.