Vacinação universal contra hepatite A no Brasil : análise da cobertura vacinal, incidência de hepatite A e persistência da imunidade em coorte de crianças vacinadas há mais de cinco anos

Abstract

In 2014, the National Immunization Program (PNI) of Brazil introduced a vaccination program against hepatitis A virus (HAV) similar to the Argentine one, providing a single dose of the monovalent inactivated virus vaccine for children from 12 months of age. Epidemiological analyzes of vaccination coverage (VC) and the incidence of hepatitis A are important indicators for the evaluation of immunization programs. In addition, it is essential to carry out follow-up studies, aiming to determine the longevity of immunological memory against HAV in this population. This study analyzed the VC of hepatitis A and its relationship with the incidence of new cases reported between 2014 and 2018, as well as the persistence of immunity in a cohort of children vaccinated more than 05 years ago. To verify the VC and the incidence of hepatitis A, we used secondary data obtained from the open access electronic sites of the Ministry of Health, the Department of Informatics of the Unified Health System (DATASUS). The VC in this period varied between 60.13% and 97.07%. Despite the insufficient VC, there was a reduction in the incidence of hepatitis A throughout Brazil concomitant with the start of vaccination. The persistence of immunity against HAV five years after vaccination with a single dose of inactivated virus vaccine was investigated among 109 children from an initial cohort of 236 (46.2%). Anti-HAV antibody analyzes were identified in 64.2%. Cellular immune response assays demonstrated a stimulation of effector T cells, with interferon-gamma (IFN-y) production in 34.3% of the 67 samples analyzed. Of the 37 anti-HAV negative samples stimulated with the VP1 antigen, 12 produced this cytokine (IFN-y). The cellular immune response of children with reactive and non-reactive anti-HAV antibodies was similar. Final evidence of immunity (humoral and/or cellular) against HAV was found in 82 children (76.6%). These findings corroborate that the strategy of vaccination with a single dose against HAV in Brazil has been successful so far, due to the significant drop in the incidence of the disease. However, it is important to be aware of reports of new cases of hepatitis A, and to keep an eye on these data, as well as to schedule new evaluations of cohorts of children vaccinated with a single dose, in order to assess the need for a booster dose in the future. Likewise, efforts to improve VC indices seem justified, with the aim of further reducing the incidence of this condition in our country.