The Impact of Community Pharmacy Utilization of Immunization Information Systems on Vaccination Rates: Results of a Clustered Randomized Controlled Trial

ABSTRACT Background Adult immunization rates in the US remain low. More convenient access to immunization information systems (IIS) may improve vaccination rates. Objective The objective of this multi-level, clustered, randomized controlled study was to measure the impact of providing pharmacists with software and training to query IIS for patient vaccine history/recommendations on adult influenza, pneumococcal, herpes zoster, and Td/Tdap vaccination rates. Methods California Rite Aid pharmacy districts were randomized into intervention/control groups using stratified randomization based on baseline influenza vaccination rates. Store demographic characteristics were collected at baseline (January 1–December 31, 2018). During follow-up (April 1, 2019–March 31, 2020), intervention group stores received access to ImmsLink®, software that allows healthcare providers to review immunization records from IIS and identify a patient’s recommended vaccinations. The difference-in-difference between intervention and control groups compared the changes in vaccination rates from baseline to follow-up by calculating adjusted ratios of risk ratios (RRRs). Analysis was performed at the store level. Results Thirty-six districts comprising 501 Rite Aid stores (intervention: n=244 stores; control: n=257) were included. We found no significant differences in vaccination rates between groups: influenza, 19–64 years (adjusted RRR=0.99, 95% confidence interval: 0.83–1.17); influenza, ≥65 years (1.02, 0.86–1.22); herpes zoster (1.07, 0.90–1.28); pneumococcal (0.95, 0.80–1.14); Td/Tdap (0.88, 0.73–1.05). Reasons that recommended vaccines were not given in the intervention group included: patient deferred to future visit, patient declined, patient already received the vaccination, patient declined due to cost, or vaccine was unavailable. Overall, pharmacist engagement with ImmsLink was low. Conclusion Providing pharmacists with software and training to query IIS did not improve vaccination rates compared with control pharmacies in this study. Factors such as an inconvenient interface or inadequate training or motivation may have caused low engagement with the software and should be considered in future interventions.