The impact of pharmacy-based immunization services on the likelihood of immunization in the United States

Abstract Objectives A major policy to increase immunization rates against infectious diseases in the United States has included pharmacy-based immunization services. We aimed to determine the impact of pharmacy-based immunization services on the likelihood of adult influenza and pneumococcal immunization. Design National individual-level immunization data were merged with pharmacy-level data on the availability of immunization services for 8466 pharmacies from a national pharmacy chain. County-level variation in availability of vaccines from 2006 to 2010 was used to characterize exposure to immunization services. We used a longitudinal logistic regression model to estimate the impact of pharmacy-based immunization services on the outcomes of interest. Setting and participants We conducted the main analysis in the U.S. adult population. We conducted subgroup analyses of high-risk populations, including people 65 years of age or older. Outcome measures Odds of being immunized for influenza or pneumococcal disease after exposure to the service compared with before the service while controlling for existing trends in immunization rate growth and other confounders. Results Each additional year of exposure to pharmacy-based immunization services was associated with a 1.023 (CI 1.012–1.034) greater odds of reporting an influenza immunization and a 1.016 (CI 1.006–1.027) greater odds of reporting a pneumococcal immunization. Five years after national implementation, we estimate that 6.2 million additional influenza immunizations and 3.5 million additional pneumococcal immunizations are attributable to pharmacy-delivered immunization services each year. Subgroup analyses further indicate that the policy increased the odds of immunization for both diseases over time among adults 65 years of age or older (influenza odds ratio [OR] 1.025, CI 1.013–1.038; and pneumococcal OR 1.026, CI 1.010–1.042). Conclusion Pharmacy-based immunization services increased the likelihood of immunization for influenza and pneumococcal diseases, resulting in millions of additional immunizations in the United States.