Real-world Effectiveness of the Influenza Vaccine in Young Children

Influenza causes substantial illness and healthcare utilization among children. Randomized clinical trials (RCTs) demonstrate that the influenza vaccine reduces influenza illness detectable via active surveillance, but RCTs typically have insufficient samples to examine economically meaningful outcomes such as healthcare provider visits. In this study we document that children aged two through five whose well-child visits occur when the seasonal influenza vaccine is broadly available are 23.4 percentage points more likely to be vaccinated than those whose visits do not. Using large administrative healthcare datasets, we leverage this variation in vaccination rates to show that the influenza vaccine reduces outpatient and emergency department visits significantly. The results imply that making pediatric influenza vaccinations more convenient could substantially increase vaccination rates and reduce healthcare expenditures.