A study conducted in Brazil and reported in an article in Vaccines shows that in the São José do Rio Preto region in the northwest of São Paulo state, only 75.8% of children aged 0-15 have antibodies against measles.
The proportion considered ideal to prevent outbreaks of the disease is 94%. The findings are in line with other recent surveys showing a drop in child vaccination rates in Brazil since 2015.
This is yet another warning shout that Brazilian children aren't achieving herd immunity and are susceptible to infection. We can see the results in practice: measles was eradicated but has now come back in our country." Maurício Lacerda Nogueira, professor at the São José do Rio Preto Medical School (FAMERP) and last author of the article
The study was funded by FAPESP via two projects (13/21719-3 and 19/06572-2).
The researchers analyzed blood samples collected from 252 children between December 2018 and November 2019 in search of specific immunoglobulin (IgG) antibodies against measles. The children had been admitted to FAMERP's hospital with suspected dengue and gave blood for analysis during clinical examination. The samples were used to determine measles seroprevalence. They were divided into five groups according to age: up to 1 year (unvaccinated); 1 year-2 years (the age at which the first and second doses of the measles vaccine should be taken); 2-5 (when the child should be fully immunized against measles); 5-10; and 10-15. The vaccination rate was less than 80% in all groups.
"All age groups are below the ideal rate, but the most troubling is the 2-5 age group, where the rate is 70%," Nogueira said. "These children should have been vaccinated in the last two or three years. The COVID-19 pandemic may have contributed to this shortfall, but the drop in vaccine coverage in Brazil is a problem that began earlier, in 2015 or…