Measles Vaccination Coverage and Risk of Re-Emergence in Brazil

Measles is a highly contagious viral disease whose prevention depends on high vaccination coverage. In this context, the MMR (measles-mumps-rubella) vaccine, offered free of charge by SUS, has efficacy above 95% after two doses. Although Brazil was certified as free of endemic measles circulation in 2016, this status was lost in 2018 due to declining vaccination coverage. Reduced coverage, intensified by the COVID-19 pandemic, increased the risk of reintroduction and sustained circulation of the virus. This study analyzes measles vaccination coverage data from 2015 to 2023 and its impact on the risk of re-emergence. Ecological, descriptive and retrospective study with analysis of aggregated secondary data from the Programa Nacional de Imunizações, DATASUS, and official bulletins of the Ministério da Saúde. Vaccination coverage for the 1st and 2nd doses of the MMR vaccine between 2015 and 2023 and records of confirmed measles cases in the same period were evaluated. The vaccination coverage target recommended by the Ministério da Saúde is 95% for both doses. The analysis was descriptive, considering annual trends and regional variations. In 2015, 1st-dose MMR coverage was 96.1%. In 2017, coverage dropped to 85.2%, with a slight recovery in 2019 (91.4%), but in 2020, during the pandemic, it fell to 79.7%. In 2021, it reached the lowest level of the period (71.4%). In 2022 and 2023, modest improvement was observed, reaching 77.3% and 80.6%, respectively. Coverage of the 2nd dose remained persistently below target, oscillating between 60% and 70% in most years. From 2018 onward, Brazil again recorded measles cases. In 2019, more than 18,000 confirmed cases occurred, with outbreaks in several states. Despite reduced cases in 2020 and 2021, localized outbreaks continued to be identified through 2023, with confirmed cases in states such as Roraima, Amapá and São Paulo. The analysis reveals a progressive decline in measles vaccination coverage from 2015 to 2023, exacerbated by the COVID-19 pandemic. This resulted in loss of elimination status in 2018 and outbreaks in 2019. Low adherence to the second dose, misinformation and regional inequalities reinforce the need for coordinated actions to restore coverage and highlight the risk of re-emergence.