Epidemiologic patterns of hepatitis A infection during the pre-vaccination era: A population-based survey in Tunisia in 2015

Background: In the 1980s, Tunisia was considered a country of high endemicity for hepatitis A virus (HAV). Since 20 0 0, an epidemiologic shift has led to an increased incidence of symptomatic and severe forms of HAV infection. Objectives: In 2015, we conducted a cross-sectional nationwide household-based hepatitis A virus (HAV) seroprevalence study in the total population regardless of age, sex, or geographic origin using a stratified sampling design to make an overview of the HAV epidemiologic situation in Tunisia before vaccine implementation. Results: A total of 6,322 individuals were enrolled. The HAV prevalence was 78.8%. The anti-HAV IgG seropositivity rate increased from 16% for ages 5-9 years to 45% for ages 10-14 years, 67% for ages 15-19 years, 87% for ages 20-24 years, and > 90% for older age groups, which suggested an age at midpoint of population immunity (AMPI) in late adolescence. It was significantly higher in rural areas ( P < 10 -3) and varied significantly between and within regions ( P < 10 -4). Conclusions: In this study, although the overall AMPI suggestsintermediate endemicity, the regional AMPI varies from intermediate to very high endemicity profiles attributable to different socioeconomic determinants and conditions of sanitation and hygiene. In addition, it provides insights for the best decisions in terms of vaccination strategies. (c) 2022 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )