A nationwide survey of past hepatitis A infections among Canadian adults

• Published in: Vaccine 2010-07, Vol.28 (32), p.5174-5178
• Main Authors: Scheifele, David W, De Serres, Gaston, Gilca, Vladimir, Duval, Bernard, Milner, Ruth, Ho, Margaret, Ochnio, Jan J
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Age; Aged; Allergy and Immunology; Applied microbiology; Biological and medical sciences; Canada - epidemiology; Confidence intervals; Education; Ethnicity; Family income; Female; Fundamental and applied biological sciences. Psychology; Health Surveys; Hepatitis; Hepatitis A; Hepatitis A - epidemiology; Hepatitis A Antibodies - analysis; Hepatitis A vaccine; Hepatitis A virus; Hepatitis antibodies; Human viral diseases; Humans; Immunization; Infections; Infectious diseases; Logistic Models; Logistics; Male; Medical research; Medical sciences; Microbiology; Middle Aged; Multivariate analysis; Population; Prevalence; Provinces; Questionnaires; Risk Factors; Sample size; Software; Studies; Surveys and Questionnaires; Travel; Vaccines; Vaccines, antisera, therapeutical immunoglobulins and monoclonal antibodies (general aspects); Viral diseases; Viral hepatitis; Womens health; Young Adult; Young adults
• ISSN: 0264-410X; 1873-2518
• DOI: 10.1016/j.vaccine.2010.05.076

Abstract Background Hepatitis A virus (HAV) infection rates in Canada are low and declining. A nationwide pediatric serosurvey in 2003 confirmed that HAV infection is uncommon in children. Additional seroepidemiological data for adults would help to guide domestic use of HAV vaccines. Methods A country-wide survey of HAV antibody positivity and selected risk factors was conducted among 18–69 year olds identified by random digit dialing, in samples proportional to regional populations. Volunteers were sent study materials and returned oral fluid and completed questionnaires by mail. An ultra-sensitive assay was used to detect HAV antibody in oral fluid. Multiple logistic regression was used for risk factor assessment. Results Of 2104 potential study participants, 1552 (74%) returned an adequate oral fluid specimen and questionnaire. Anti-HAV was detected in 509 individuals (33%) and was associated with birth in HAV endemic areas, self-reported hepatitis A vaccination, prior travel to endemic areas, and increasing age. Only 15% reported having been vaccinated. Among Canadian-born, non-vaccinated participants anti-HAV was present in 20%, ranging regionally from 14% to 30%. Age-specific positivity rates in this subset were: 18–29 years 2.6%; 30–39 years 6.1%; 40–49 years 11.4%; 50–59 years 26.4% and 60–69 years 45.9%. Travel to HAV-endemic countries was reported by 55% of participants but only 24% of travelers had been vaccinated. Conclusions Past HAV infection rates among Canadian-born, non-vaccinated individuals are low in young adults and increase by two-fold per age decade. Travel to endemic areas is a significant risk factor, amenable to prevention by greater use of HAV vaccine.