2.1 Patients
This study enrolled patients older than 15 years of age who were diagnosed with influenza and required hospitalization between November 2014 and August 2019. Formal and collaborating members of the JRS throughout the country were invited to participate in the study. The members logged into the internet-surveillance system 3and registered the patients’ data. The required data included age, sex, medical professional or not, presence of family transmission, diagnostic methods, type of influenza, the onset date, the hospitalized date, vaccination history for both influenza and pneumococcus, underlying diseases or comorbidity, smoking habits, presence of obesity (body mass index≥30), reasons for hospitalization, presence of pneumonia, category and types of pneumonia, causative pathogens of pneumonia, antiviral drugs used, presence of oxygen therapy or artificial ventilation, antimicrobials used, and outcomes. The system sent reminder mails 14, 30, and 90 days after registration to follow up on the original registration. The internet surveillance committee of the JRS extracted and analyzed the registered data twice a year.
This study was registered with UMIN (UMIN000015989) and was approved by all participating institutional review boards. All patients gave their informed consents by being given opportunities to refuse to participate.