Real-world estimation of the pneumococcal vaccination coverage among high-risk population in the unified health system in Brazil: an administrative database analysis

Immunization against pneumococcal disease (PD) for individuals with certain coexisting health conditions is recommended by the National Immunization Program (NIP) in the Unified Health System (SUS) in Brazil. There are uncertainties regarding the size of the population at risk and the proportion of high-risk individuals assessed at the Reference Centers for Special Immunobiologicals ( Centros de Referência para Imunobiológicos Especiais , CRIE). Objectives were to assess the high-risk population size from a claims database, to estimate the vaccination coverage rate, and to assess the proportion of complete, incomplete and non-conforming vaccination schemes. ICD-10 and procedure codes related to high-risk health conditions were defined, together with proxies of disease activity and severity. Data from the outpatient information system of medium-to-high complexity levels of care, and the information system of immunobiologicals were analyzed. Encrypted identifiers were used to count distinct individuals from November 2021 to October 2023. Complete vaccination scheme was defined as at least one PCV13 and two or more PPS23 doses; incomplete vaccination scheme as one PCV13 and less than two PPS23 doses; and non-conform vaccination scheme as more than one PCV13 and less than two PPS23 doses. The estimated size of the high-risk population was 1,609,181 individuals. Coverage rate for having received at least one dose of PCV13 was estimated at 45.5 % and for the complete vaccination scheme at 3.5 %. Most vaccination schemes were incomplete or non-conform. A small proportion of high-risk individuals were considered as having received the complete pneumococcal vaccination scheme, possibly due to issues such as the high complexity of the vaccination scheme, and limited access to CRIE, due to the continental size of Brazil and the concentration of CRIE in large cities. These findings should be interpreted with caution, considering the inherent limitations of the data sources used. • The size of the population at high risk for pneumococcal diseases in in Brazil was estimated. • Around 1.6 million individuals, with predominance of cancer and HIV/AIDS patients, were identified. • The vaccination coverage was estimated at 45.5% of the high-risk population. • Among vaccinated individuals, only 7.6 % received the recommended complete scheme. • Study limitations include the use of administrative database for the population size estimate.