State-Level Variations and Factors Associated with Adult Vaccination Coverage: A Multilevel Modeling Approach

Adult vaccination coverage in the United States: A database analysis and literature review of improvement strategies

Despite vaccines being instrumental in reducing vaccine-preventable disease, adult vaccination rates in the United States (US) are below optimal levels. To better understand factors affecting vaccination rates, we analyzed trends in adult vaccination coverage using data from the Behavioral Risk Factor Surveillance System (BRFSS) and conducted a targeted literature review (TLR) on interventions to improve adult vaccination rates in the US. Both the BRFSS analysis and the TLR focused on influenza; pneumococcal disease; tetanus and diphtheria or tetanus, diphtheria, and acellular pertussis; herpes zoster; and human papillomavirus vaccination for US adults aged 18-64 years. The TLR additionally included hepatitis A and hepatitis B vaccination. Vaccination coverage rates (VCRs) and changes in VCRs were calculated using the 2011-2019 BRFSS survey data. For the TLR, the MEDLINE and MEDLINE In-Process databases were searched for articles on vaccination interventions published between January 2015 and June 2021. The BRFSS analysis showed that changes in VCRs were generally modest and positive for most states over the study period. The TLR included 32 articles that met the eligibility criteria; intervention strategies that improved adult vaccination outcomes incorporated an educational component, vaccination reminders or reinforcement at the point of care, or authorized non-clinician members of the healthcare team to vaccinate. Furthermore, interventions combining more than one approach appeared to enhance effectiveness. The strategies identified in this TLR will be valuable for policymakers and stakeholders to inform the development and implementation of evidence-based policies and practices to improve adult vaccination coverage.

State policies increase vaccination by shaping social norms

In a survey and four preregistered experiments, we examined if implementing a vaccine-promoting policy is likely to encourage vaccination by shaping the norms of a society. By combining state-level policy data with a longitudinal survey, we found that vaccine-supportive policies and laws are associated with more positive social norms. To establish a causal effect, we conducted four preregistered experiments to gauge the impact of policies, including the government recommendation for children to receive the COVID-19 vaccine and changes in funding for immunization programs. We find that vaccine-supportive policies strengthen the intention to receive an additional recommended COVID-19 booster shot and the intention to vaccinate children against COVID-19. We also find that these effects are mediated by the promotion of social norms supportive of vaccination. In this context, communicating about laws and policies in favor of vaccination may create a culture of vaccination and increase vaccination coverage.

Real-world evidence on adherence and completion of the two-dose recombinant zoster vaccine and associated factors in U.S. adults, 2017-2021

INTRODUCTION

Poor compliance with adult vaccination recommendations contributes to substantial disease burden. Evidence on adherence, completion, and completion timeliness for the 2-dose recombinant herpes zoster vaccine (RZV) and factors associated with these outcomes is limited and not readily generalizable for the entire U.S.

METHODS

This retrospective, observational study examined adherence, completion, and the impact of sociodemographic, clinical and geographical factors among U.S. adults ≥ 50 years receiving RZV (4/20/2017 to 3/31/2021), using a large, geographically representative administrative claims database. Continuous enrollment in a medical benefit plan for six months prior to and following the index date (first observed vaccine dose) was required. Adherence was defined as receipt of the 2nd dose within 2-6 months, per label recommendation. Completion (receipt of all doses) was assessed at 6, 12, 18, and 24 months.

RESULTS

Among 726,352 adults included, the adherence rate was 71.8%. Among 208,311 adults with 24-month follow-up, the completion rate was 72.3% after 6 months and 86.2% after 24 months. Logistic regression showed low adherence/completion was associated with younger age, Black or Hispanic race/ethnicity, lower income, lower educational attainment, and possessing commercial rather than Medicare healthcare insurance. Recipients identified using pharmacy claims had much higher adherence (74.0%) than those identified using medical claims (48.0%).

CONCLUSIONS

Adherence and completion rates for RZV are suboptimal, especially for adults aged 50-64, racial/ethnic minorities, individuals with lower socio-economic status and those without Medicare insurance. More research and public health efforts are needed to understand and address potential barriers to RZV uptake, adherence and completion.