{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,2,25]],"date-time":"2026-02-25T23:00:16Z","timestamp":1772060416760,"version":"3.50.1"},"reference-count":31,"publisher":"European Centre for Disease Control and Prevention (ECDC)","issue":"37","license":[{"start":{"date-parts":[[2025,9,18]],"date-time":"2025-09-18T00:00:00Z","timestamp":1758153600000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2025,9,18]]},"abstract":"<jats:p>BACKGROUND: Hepatitis A incidence in Portugal declined from 20.1 to 0.4\/100,000 population between 1987 and 2023, changing non-vaccinated population susceptibility. This shift has contributed to more frequent outbreaks, including in 2024\u201325, highlighting the need to enhance surveillance and integrate serological data.<\/jats:p>\n               <jats:p>AIM: We aimed to describe the exposure profile of the Portuguese population to hepatitis A virus (HAV) over time by estimating and comparing the seroprevalence of hepatitis A in two nationwide surveys.<\/jats:p>\n               <jats:p>METHODS: Data from two cross-sectional seroprevalence studies performed in 2001\u201302 and 2015\u201316 in the population aged\u2009\u2265\u20092 years were analysed. Seroprevalence was weighted for population distribution by age, sex and region, and then analysed by birth cohort (1911 -2014) and compared using Poisson regression.<\/jats:p>\n               <jats:p>RESULTS: Overall prevalence of anti-HAV IgG antibodies was 67.3% (95%\u202fCI:\u202f64.2\u201370.3) in 2001\u201302 (n\u2009=\u20091,642) and 56.3% (95%\u202fCI:\u202f52.4\u201360.2) in 2015\u201316 (n\u2009=\u20092,052), showing an 11-percentage-point decline. Birth cohort analysis revealed consistent seroprevalence within each cohort in both surveys, i.e. seroprevalence for the 1981\u201390 birth cohort was 16.7% and 18.7%, respectively, suggesting that higher seroprevalence is more closely associated with birth cohort (cohort effect) rather than a specific time point. Additionally, we found that individuals aged\u2009\u2265\u200930 years, born before the 1980s, and those with lower education had higher seroprevalence.<\/jats:p>\n               <jats:p>CONCLUSIONS: The immunological profile of anti-HAV antibodies in the Portuguese population has shifted over the last decades. High susceptibility and shifting age distribution of Hepatitis A-seropositive individuals highlight the need to revise future vaccination strategies in Portugal.<\/jats:p>","DOI":"10.2807\/1560-7917.es.2025.30.37.2500020","type":"journal-article","created":{"date-parts":[[2025,9,19]],"date-time":"2025-09-19T10:15:42Z","timestamp":1758276942000},"update-policy":"https:\/\/doi.org\/10.2807\/1560-7917.es.crp2020","source":"Crossref","is-referenced-by-count":1,"title":["Tracking epidemiological shifts in hepatitis A in Portugal: a comparison of seroprevalence between two nationwide surveys, 2001 to 2002 and 2015 to 2016"],"prefix":"10.2807","volume":"30","author":[{"given":"Vera","family":"Manageiro","sequence":"first","affiliation":[{"name":"Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA), Lisbon, Portugal"}]},{"given":"Rita","family":"Matos","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA), Lisbon, Portugal"}]},{"given":"Paula","family":"Palminha","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA), Lisbon, Portugal"}]},{"given":"Helena","family":"Cortes-Martins","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA), Lisbon, Portugal"}]},{"given":"Baltazar","family":"Nunes","sequence":"additional","affiliation":[{"name":"Comprehensive Health Research Center (CHRC), Centre for Public Health Research (CISP), National School of Public Health, NOVA University of Lisbon, Lisbon, Portugal"},{"name":"Department of Epidemiology, National Health Institute Doutor Ricardo Jorge (INSA), Lisbon, Portugal"}]},{"given":"Rita","family":"de Sousa","sequence":"additional","affiliation":[{"name":"Department of Infectious Diseases, National Institute of Health Doutor Ricardo Jorge (INSA), Lisbon, Portugal"}]}],"member":"7995","reference":[{"key":"r1","doi-asserted-by":"crossref","unstructured":"Shouval D. 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