Yellow Fever Case-Fatality in the State of Minas Gerais (1980–2024): Reflections of the National Immunization Program

Yellow fever (YF) is an endemic arboviral disease with high morbidity and mortality in Brazil. There is no specific antiviral treatment; however, it is preventable through a highly effective vaccine that provides lifelong protection and has been available through the National Immunization Program (PNI) since 1999. About 12% of cases progress to liver and kidney failure, jaundice, and severe hemorrhage, with case-fatality rates up to 50% in this group. To compare YF case-fatality rates among residents of Minas Gerais (MG) before and after the introduction of the YF vaccine into the PNI, analyzing deaths from 2000 to 2024 by age group (0–26 years and >26 years). This observational, descriptive, retrospective epidemiological study comparatively evaluated YF case-fatality rates in 1980–1999 and 2000–2024, using data from DataSUS and the National Yellow Fever Epidemiological Surveillance Manual. Cases were grouped by vaccination period (pre- and post-PNI). For 2000–2024, the epidemiological profile of deaths was analyzed by age group: 0–26 years and >26 years. The case-fatality rate from 1980 to 1999 was 38.3%, decreasing to 34.2% from 2000 to 2024, a reduction of 4.1%. In the latter period, 376 deaths were recorded, of which 95.2% occurred among people older than 26 years; vaccination status could not be determined. There was a reduction in YF case-fatality after inclusion of the vaccine in the PNI, indicating a positive impact of immunization. Most deaths occurred in individuals >26 years who were not vaccinated by the PNI, reinforcing the vaccine’s effectiveness in reducing deaths and the importance of vaccination strategies for groups not covered by routine vaccination. A potential underreporting of data before 2000 (pre-DataSUS period) should be considered. Introduction of the YF vaccine into the PNI contributed to reducing YF case-fatality in MG, especially among individuals aged 0–26 years. The high mortality among those older than 26 years who were not vaccinated reinforces the need for vaccination campaigns targeted to this group to reduce disease morbidity and mortality.