Shortly after receiving international certification as a measles-free country in 2016, Brazil witnessed a resurgence of this viral infection, which weakens the immune system, especially in children, and can be fatal. In 2018 there were 9,300 cases, followed by 20,000 in 2019 and 8,100 in 2020. These numbers were significantly higher than those observed in the previous two decades and resembled the figures from the 1990s, according to data from the Brazilian Ministry of Health. The recent comeback of the disease appears to be the result of a trend that has been escalating in recent years: a pronounced decline in vaccination coverage (see Pesquisa FAPESP issues 270 and 313). A study published in early August in PLOS Global Public Health, conducted by researchers from Brazil and the United Kingdom, assessed changes in measles, mumps, and rubella (MMR) vaccine coverage in 5,565 Brazilian municipalities, covering almost the entire country. The study identified three stages of decline between 2006 and 2020, with the most pronounced reductions occurring in economically disadvantaged cities and regions.
In Brazil, since 2004, MMR vaccine has been administered to children up to 8 years of age in at least two doses, with the first dose given at 12 months of age. Two booster doses are recommended for adults up to 29 years, and an additional one for individuals between 30 and 59 years of age. International health authorities, such as the Pan American Health Organization (PAHO), recommend that at least 95% of the population is vaccinated to prevent the transmission of these diseases. In 2006, virtually 100% of Brazilian children had received the first dose of the MMR vaccine, but since then this number has been steadily declining.
Overall, vaccine administration decreased from 2006 to 2020 at an average rate of 1.22 percentage points per year (ppa), as observed by the research group led by epidemiologists Maurício Lima Barreto from the Oswaldo Cruz Foundation (FIOCRUZ) in Bahia, and Elizabeth Brickley from the London School of Hygiene and Tropical Medicine, in a review of the official data from the National Immunization Program (PNI). However, the decline was not uniform. Vaccine administration fell by 0.78 ppa from 2006 to 2013, pre-economic crisis. The rate of decline increased to 2.33 ppa during the economic recession and political crisis from 2014 to 2019 and jumped to 9.75 ppa in 2019 and 2020, just before the COVID-19 pandemic and during the first year of the global health crisis. In 2020, only 80% of 1-year-old Brazilian children received the first dose of the MMR vaccine.
When municipalities were grouped by level of socioeconomic development, as measured by the Brazilian Deprivation Index (IBP), created by FIOCRUZ and the University of Glasgow in Scotland, researchers noted that in the 2,565 most economically disadvantaged municipalities, which initially had the highest rates of vaccine coverage in the country, the rate of decline was more pronounced, at 1.64 ppa from 2006 to 2020. In the 224 municipalities in the less deprived group, all located in the South and Southeast, vaccine administration declined at a 2.7 times slower rate (0.61 ppa) over the same period. The poorest cities also experienced a much steeper decline in the 2006–2013 and 2019–2020 intervals. Vaccine coverage fell by 1.59 and 14.1 ppa in the most economically disadvantaged municipalities, compared to 0.68 and 5.31 ppa in wealthier cities. Reflecting these divergent trends, the vaccine was administered to an average of 92% of children in less deprived cities in 2020 compared to 87% in the poorest ones.
The PLOS Global Public Health article corroborates findings from other studies on the decline in vaccine coverage in the country. In a paper published in 2020 in Cadernos de Saúde Pública, Luiz Henrique Arroyo and colleagues from the School of Nursing in Ribeirão Preto at the University of São Paulo (USP) evaluated regional disparities in the coverage of three vaccines (BCG, polio, and MMR) in Brazil between 2006 and 2016. They identified that in the states of Pará, Maranhão, and Bahia, the proportion of children receiving the MMR vaccine decreased at a faster annual rate than in the rest of Brazil, creating a higher risk for the emergence of outbreaks. In another study published this year in Ciência & Saúde Coletiva, epidemiologist Ana Paula Sayuri Sato, a researcher at the USP School of Public Health in São Paulo and a coauthor of the PLOS Global Public Health article, observed that the COVID-19 pandemic exacerbated health disparities in Brazil. This led to a further reduction in measles vaccine coverage in municipalities with greater social vulnerability. The decline was most significant in the North and Northeast, regions with higher levels of poverty, inequality, and lower coverage of the Federal Government’s Family Health Strategy — a program where multidisciplinary teams provide primary healthcare in communities.
There are several possible reasons to account for the decrease in vaccine coverage, ranging from increasing vaccine hesitancy to a lack of awareness of the risks associated with preventable diseases. Additionally, the vaccination schedule has become increasingly complex, with the National Immunization Program (PNI) now incorporating 17 vaccines in the childhood immunization calendar.
Epidemiologist Júlia Pescarini, another coauthor of the article, introduces yet another factor: the economy. “The rate of decline in MMR vaccine coverage accelerated amid economic crises and the ensuing reductions in healthcare spending,” notes Pescarini, who is a researcher at FIOCRUZ in Bahia and a professor at the London School of Hygiene and Tropical Medicine. “Our data align with findings from other studies showing that a lack of investment in primary healthcare facilities or vaccination campaigns may have contributed to the worsening health indicators. In addition, the SUS’s [National Healthcare System] tripartite [federal, state, and municipal] funding model means that poorer municipalities are more reliant on federal and state funds compared to wealthier ones,” she remarks.
Carla Domingues, a sociologist and epidemiologist who led the National Immunization Program (PNI) from 2011 to 2019, highlights another consequence of the economic recession. “A significant portion of the population is either unemployed or informally employed, which makes visiting vaccination centers difficult. Additionally, the previous administration eliminated the requirement for disadvantaged families to keep their children’s vaccination records up to date in order to receive social welfare benefits,” she adds.
According to infectious disease specialist Julio Croda from the Federal University of Mato Grosso do Sul (UFMS), economic incentives should be considered when devising strategies to improve vaccine uptake in Brazil. “Some studies show that one way to promote vaccination is by offering some form of financial or social benefit. In practical terms, there is a strong correlation between declining vaccination coverage and income,” he states.
However, achieving the high vaccination coverage rates seen in the past is likely to require more than just financial investment. “The unique characteristics of each locality and region should inform strategies to address the waning vaccination coverage. Population dynamics in the Amazon region are different from those in the city of São Paulo,” Domingues explains.
Scientific articles
GODIN, A. et al. Municipality-level measles, mumps, and rubella (MMR) vaccine coverage and deprivation in Brazil: A nationwide ecological study, 2006 to 2020. PLOS Global Public Health. aug. 1, 2023.
ARROYO, L. H. et al. Áreas com queda da cobertura vacinal para BCG, poliomielite e tríplice viral no Brasil (2006-2016): Mapas da heterogeneidade regional. Cadernos de Saúde Pública, vol. 36, no. 4, p. e00015619. 2020.
SATO, A. P. S. et al. Vacinação do sarampo no Brasil: Onde estivemos e para onde vamos? Ciência & Saúde Coletiva, vol. 28, no. 2, pp. 351–62. feb. 2023.
