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Published on: September 19, 2016
BCG revaccination does not protect against leprosy in the Brazilian Amazon: a cluster randomised trial
Sérgio S Cunha1, Neal Alexander, Mauricio L Barreto
1Instituto de Saúde Coletiva, Universidade Federal da Bahia, State of Bahia, Brazil. cunhatmt@hotmail.com
Background:
Although BCG has been found to impart protection against leprosy in many populations, the utility of repeat or booster BCG vaccinations is still unclear. When a policy of giving a second BCG dose to school children in Brazil was introduced, a trial was conducted to assess its impact against tuberculosis, and a leprosy component was then undertaken in parallel.
Objective:
to estimate the protection against leprosy imparted by a second dose of BCG given to schoolchildren.
Methods And Findings:
This is a cluster randomised community trial, with 6 years and 8 months of follow-up.
Study Site:
City of Manaus, Amazon region, a leprosy-endemic area in Brazil.
Participants:
99,770 school children with neonatal BCG (aged 7-14 years at baseline), of whom 42,662 were in the intervention arm (revaccination).
Intervention:
BCG given by intradermal injection.
Main Outcome:
Leprosy (all clinical forms).
Results:
The incidence rate ratio of leprosy in the intervention over the control arm within the follow-up, in schoolchildren with neonatal BCG, controlled for potential confounders and adjusted for clustering, was 0.99 (95% confidence interval: 0.68 to 1.45).
Conclusions/Significance:
There was no evidence of protection conferred by the second dose of BCG vaccination in school children against leprosy during the trial follow-up. These results point to a need to consider the effectiveness of the current policy of BCG vaccination of contacts of leprosy cases in Brazilian Amazon region.
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