Understanding predictors of pneumococcal vaccine uptake in older adults aged 65 years and older in high-income countries across the globe: A scoping review

Pneumococcal disease causes substantial morbidity and mortality in older adults. Pneumococcal polysaccharide vaccine (PPV23) is routinely recommended to reduce the disease burden in this population. However, the vaccination coverage in older adults remains suboptimal in high-income countries.We sought to understand the current landscape of published literature on the predictors of pneumococcal vaccine uptake in older adults aged 65 years and older in high-income countries, and to identify the gaps in literature to inform future research.We conducted a scoping review employing the Arksey and O'Malley framework and Joanna Briggs Methods. We searched Medline, EMBASE, CINAHL, PsycInfo and Cochrane databases. We included quantitative and qualitative studies on predictors of pneumococcal vaccination in older adults that reported older adult- and pneumococcal vaccine-specific results, conducted in high-income settings, and published in English between January 2015 and April 2020. We excluded studies assessing interventions to improve vaccine uptake. We followed the Strategic Advisory Group of Experts on Immunization Working Group Vaccine Hesitancy Determinants Matrix to map the predictors within contextual, individual and social group, and vaccine and vaccination-specific influence determinants. Studies on providers and institutions were also included and results summarized separately.We included 52 publications in our review. Most of the predictors in 39 quantitative studies belonged to the individual and social group influences (n = 12), followed by contextual influences (n = 11) and vaccine and vaccination-specific issues (n = 3). Few qualitative studies explored the barriers to pneumococcal vaccination. Only five studies examined predictors from the healthcare providers' perspective. Three studies examined the institutional characteristics as the predictors of pneumococcal vaccination in older adults.We identified enablers and barriers of pneumococcal vaccination among older adults in high-income settings. We also identified gaps in the literature and provide recommendations for future research to address the gaps.