Is the aging of acute hepatitis B occurring in Brazil

Abstract

Introduction: The prevalence of hepatitis B virus (HBV) infection has been declining nationwide throughout Brazil since the introduction of universal child vaccination. The vaccine is currently available for all ages. However, most of the adult population has not been vaccinated and may still be susceptible to it. Most of the cases reported to the Brazilian Notifiable Diseases Information System (Sistema de Informação de Agravos de Notificação - SINAN) are chronic, a consequence of early exposure in life. However, acute cases are the result of current transmission and may reveal the current dynamics of HBV circulation. Objective: To evaluate whether there is a change in the age distribution of acute hepatitis B in Brazil. Methods: To analyze the historical series of reported cases and incidence rates of acute hepatitis B by age group between 2007 and 2018, based on data reported to SINAN. Temporal trend was tested with non-parametric Cusick test. Results: The incidence rate fell from 1.02 (/ 100,000 inhabitants) in 2007 to 0.67 in 2018 (p=0.01). The drop was significant at all ages, except under 15 and over 60. The highest incidences (@1.0 / 100,000 inhab.) occurred between 20 and 59 years old. Conclusion: There is a progressive “aging” of acute hepatitis B cases in the country, probably due to the vaccine protection of younger people. A considerable portion of the older population is susceptible to HBV and may be exposed, especially by sexual route. Control measures such as vaccination and guidance for safe sex are needed.