Introduction: Influenza is the most common vaccine-preventable infection the first 5 years post-transplant. Despite the availability of safe and effective vaccines, vaccine uptake is low among high-risk transplant patients who are recommended to receive pneumococcal and annual influenza vaccines. While disparities in vaccination have been observed by race, with lower uptake among Blacks and Hispanics, little is known about the role of sociodemographic characteristics including an individual-level housing-based HOUSES index, education, marital status and geographic location (rural/urban classification) play in vaccine uptake. To improve health outcomes and vaccine coverage, we must identify and target populations with low uptake.

Methods: We conducted a cross-sectional, population-based study using the Rochester Epidemiology Project (REP), a medical records linkage system, to assess sociodemographic factors associated with influenza and pneumococcal vaccination rates among adults aged 19-64 years old with solid organ transplants, living in four counties in southeastern Minnesota. Socioeconomic status (SES) was assessed via HOUSES, measure of SES. Vaccination data was obtained from the Minnesota Immunization Information Connection (MIIC) from June 1, 2010-June 30, 2020. Influenza vaccination rate was assessed with Poisson regression models, offset by number of vaccines eligible for; pneumococcal status was assessed with logistic regression models.

Results: 468 solid organ transplant patients were identified (Table 1). Liver and lung transplant patients were least vaccinated for influenza. Influenza vaccination ranged from 52-58% over the past 10 years which was slightly higher than national averages and adults in our area who were recommended to receive pneumococcal vaccines (35-43%). Race was not significantly associated with influenza vaccine uptake when adjusted for geographic region or SES as assessed by HOUSES. If patients were up-to-date on pneumococcal vaccine they had a 26% higher influenza vaccination rate. Heart transplants recipients were least up-to-date on pneumococcal vaccines. 56% of patients were compliant with pneumococcal vaccines, with a median of 18 months undervaccinated. Those living in urban settings were significantly better vaccinated for both influenza and pneumococcus even when adjusted for all other variables (Table 2).

Conclusions: Rates of vaccination were well below national goals, even though transplant recipients did better than other national estimates of this high-risk group. The transplant process includes rigorous review of vaccinations with close follow-up, and despite this many patients remained undervaccinated. Further investigation is needed to understand and address barriers to vaccination among transplant recipients. This is especially important among subgroups with particularly low rates of adoption, seen particularly in those outside urban areas.