Current usage and effectiveness of influenza medications and factors regarding the time taken to alleviate fever based on postcard questionnaire survey

BACKGROUND: After the A/H1N1 influenza pandemic in 2009, two new drugs against the influenza virus, laninamivir and peramivir, were released in 2010 in Japan. We investigated the current usage and effectiveness of influenza medications and factors related to the time taken to alleviate fever. METHODS: Patients diagnosed with influenza during the 2012‐2013 season in Osaka Prefecture answered a postcard questionnaire that collected data regarding their demographic characteristics, flu vaccination status, symptoms, prescribed drugs, and drug‐related adverse events. RESULTS: The use of laninamivir consistently increased over the 3‐year period and was prescribed at a similar rate as oseltamivir during the last year (39% and 45%, respectively). None of the neuraminidase inhibitors had a significant effect on the fever or other symptoms of influenza infection (P=.59 and P=.70, respectively). Vaccinated influenza patients experienced fever for a significantly longer duration than the nonvaccinated patients (P=.04). However, multivariate analysis showed that only influenza virus type, but not vaccination status, was related to the alleviation of fever within 2 days. CONCLUSIONS: There were no significant differences of effects on fever and symptoms among neuraminidase inhibitors. Virus type was only related to the alleviation of fever.