Measuring the Social and Externality Benefits of Influenza Vaccination

Vaccination represents a canonical example of externalities in economics, yet there are few estimates of their magnitudes. I provide evidence on the social and externality benefits of influenza vaccination in two settings. First, using pre-existing differences in state-level vaccination rates interacted with exogenous annual variation in vaccine quality, I estimate of the impacts of aggregate vaccination rates on mortality and work absences in the United States. Scaled nationally, I find that a one percentage point increase in the vaccination rate results in 1,134 fewer deaths and 8.9 million fewer work hours lost due to illness each year. The mortality reductions are concentrated among individuals 75 and older, but over half of the effect is attributable to the vaccination of people under 75, suggesting a considerable externality effect. Second, I examine a setting in which vaccination is targeted at a group with extremely high externality benefits: vaccination mandates for health care workers. I find that mandates lead to reductions in hospital diagnoses for influenza in affected counties, consistent with substantial externality impacts. For both the general population and the population of health care workers, the estimates suggest that programs increasing vaccine take-up are likely to be cost-effective under reasonable assumptions about the costs.