Prevalence of hepatitis B infection in children under 5 years old on indigenous communities of the Peruvian Amazonia after immunization interventions

To determine the prevalence of hepatitis B virus (HVB) infection and seroprotection in indigenous children living in three draining basins of the Peruvian Amazon. A cross sectional study was conducted in three draining basins (Pastaza, Morona and Lower Urubamba rivers), home to six indigenous populations: shapra, candoshi, machiguenga, yine, ashaninka and nanti. Children under 5 years were included. A survey and review of the vaccination card was applied, and a serum sample was processed with ELISA for HBsAg, total anti-HBc and anti-HBs was obtained, defining "seroprotected children" if they were reactive to anti-HBs and non-reactive to anti-HBc. A total of 742 children under 5 years old residents in six indigenous communities were included in the study. 380 (51.2%) were male and 169 (22.9%) one year old or younger. Regarding recorded HVB vaccination on the card, only 434 (58.5%) had received three doses; 208 (38.8%) received the first dose within 24 hours. No cases were detected with HBsAg. 88.8% of children had seroconverted, varying between 67-100% across the populations. No cases of chronic HBV infection were detected. The vaccination coverage by card revision is low, contrasting with high seroconversion rates.