Avaliação da imunidade contra os vírus das hepatites A e B em adolescentes escolares

Abstract

Hepatitis A and B still represent an important public health problem. The inclusion of the hepatitis B virus vaccine in our National Immunization Program (1998), with the less distant inclusion for hepatitis A (2014), was fundamental for the control of these infections in our country. However, in recent data from the Ministry of Health, a marked change in the epidemiological profile of both infections has been gaining attention. In addition, data in the literature on the persistence of anti-HBs induced by the hepatitis B vaccine are heterogeneous and occasionally rare in our country. There is also little information on the current prevalence of acquired natural immunity related to hepatitis A. Within this context, the main objective of this study is to determine immunity against hepatitis A and B virus in school adolescents. Secondary objectives are: (i) to determine the natural and acquired immunity against hepatitis B, (ii) to determine the vaccination coverage for hepatitis A and B. This is a cross-sectional study, with prospective inclusion of school adolescents between 15-18 years old, in which demographic and clinic data, vaccination history, and blood collection were obtained. The serological analysis includes anti-HBs quantitative, anti-HBc qualitative, and anti-HAV IgG qualitative, determined using the Electrochemiluminescence method (Cobas – Roche). 125 students were included in our sample (35% male, mean age 16+1). There was proof of vaccination in 80% (n=100), through the presentation of the vaccination card. We obtained 41% (n=51) of the anti-HBs sample ≥ 10 mIU/mL, all anti-HBc non-reactive, showing that the immunity found is vaccine-based. The same prevalence was found to be 41% (n=41) in the subgroup of adolescents with proof of vaccination. There was no statistically significant difference in any variable between the anti-HBs groups greater/equal or less to 10 mIU/mL. The prevalence of reactive anti-HAV IgG was 32% (n=40). Among those considered vaccinated for hepatitis A (n=36), 92% (n=33) were immune. Only 8.9% (n=7) of students not vaccinated for hepatitis A were immune. In conclusion, we obtained a low prevalence of anti-HBs at protective levels, a high prevalence of prolonged immunity resulting from hepatitis A immunization, and a low exposure to the hepatitis A virus in childhood.