The Impact of Pharmacy-Based Immunization on Vaccination Rates and Prevalence of Influenza Virus

From the 1990s through 2000s, states have changed pharmacist occupational regulations to allow provision of vaccinations. Little is known about the effects of these changes. This study estimates the impact of pharmacy-based immunization (PBI) regulations on seasonal influenza vaccination rates, provider source and health outcomes in the United States from 1996-2012. The evolution of PBI regulations was tracked in every state from 1996-2012 and influenza vaccination rates analyzed pre- and post-regulatory change in a quasi-experimental study design. Vaccination rates were determined from the National Behavioral Risk Factor Surveillance System (BRFSS). The outcomes were regressed on regulatory changes and other individual covariates (age, gender etc.) in a linear probability model. From 1996-2012, a total of 5,171,240 respondents were surveyed for the BRFSS. Excluding missing data, 3,866,450 respondents were included for analysis. Regulatory changes allowing PBI did increase the proportion of individuals vaccinated by 1.0% (95% CI: 0.3, 3.0). However this marginal increase in vaccination rates belies a complex underlying effect modification by age. In the presence of regulations, vaccination rates increase for those less than 65 years old (7.4%, 95% CI: 5.5, 10.4) but decrease for those 65 or older (-4.9%, 95% CI: -6.7, -2.3). PBI also appears to decrease the proportion of individuals who receive their vaccinations in physician offices by -1.7% (95% CI: -2.7,-0.7). No impact on health outcomes was observed. PBI regulations promoting pharmacy-based immunization have heterogeneous effects on vaccination by patient population. We observed increases in vaccination in certain subgroups following a change in regulation and decreases for others. Additionally, the regulations were associated with a decrease in vaccination receipt in physician offices. Further research focused on the potential effect modification of PBI by age and more robust data-sources will help further validate these findings.