Temporal trend of influenza vaccination coverage among older adults in Brazil.

This study aimed to assess influenza vaccination coverage among older adults and its temporal trends in Brazil, its regions, and federative units from 2000 to 2019. This ecological time series study utilized data from the National Immunization Program Information System (SI-PNI). The sample comprised vaccine doses administered and the target population each study year, stratified by territorial unit. Vaccination coverage was calculated as the proportion of the target population effectively vaccinated, and temporal trends were assessed using the Prais-Winsten generalized linear regression model. Significant fluctuation in vaccination coverage was observed in Brazil, with the lowest coverage recorded in 2000 (72.53%) and the highest in 2018 (97.16%). Amapá presented the highest average vaccination coverage over the period (95.51%), while São Paulo had the lowest (79.71%). Santa Catarina and São Paulo stood out for their highest annual variation in vaccination coverage, and increasing vaccination coverage trends were noted in 15 federative units of the country. In summary, influenza vaccination coverage among older adults showed fluctuations over 20 years, with a growing trend towards vaccination adherence in most federative units.