Effects of influenza vaccine and sun exposure time against laboratory-confirmed influenza hospitalizations among young children during the 2012-13 to 2015-16 influenza seasons

Background: Influenza is a major cause of acute respiratory infection burden worldwide, leading to many hospitalizations. An annual influenza vaccine is believed to be the best way to prevent influenza-related illnesses. We focused on the efficacies of other possible preventive measures such as increasing sun exposure time and dietary supplements to prevent these illnesses. Methods: We conducted a matched-pair case-control study along with the Taiwan Pediatric Infectious Disease Alliance. We included influenza-related hospitalized patients with age ranging from 6 months to 5 years during the 2012-2013, 2013-2014, 2014-2015, and 2015-2016 influenza seasons. The controls were comparable to cases in age, sex, and residential area and had no influenza-related hospitalization records in the same season. We extracted data from vaccination histories and got the patients' guardians to complete questionnaires. Data were analyzed using conditional logistic regression. Results: We enrolled 1514 children (421 influenza-infected cases and 1093 controls) in the study. We found seasonal influenza vaccination to be an independent protective factor against hospitalizations owing to influenza [p < 0.01; odds ratio (OR), 0.427; 95% confidence interval (CI), 0.306-0.594]. Children with mean sun exposure time of >7 h/week had a significantly lower risk of influenza-related hospitalizations than those with the mean sun exposure time of <= 7 h/week (p < 0.05; OR, 0.667; 95% CI, 0.491-0.906). Conclusions: Seasonal influenza vaccination effectively prevents influenza-related hospitalizations in children aged <= 5 years. Besides, >7 h of sun exposure/week may also be associated with lower risk of influenza-related hospitalizations in children. Copyright (C) 2019, Taiwan Society of Microbiology. Published by Elsevier Taiwan LLC.