Long-term immunogenicity of inactivated hepatitis A vaccine: Follow-up at 15 years

Article type: Research Article

Authors: Byrd, Kathy K.^; | Bruden, Dana L. | Bruce, Michael G. | Bulkow, Lisa R. | Zanis, Carolyn L. | Snowball, Mary M. | Homan, Chriss E. | Hennessy, Thomas W. | Williams, James L. | Dunaway, Eitel | Chaves, Sandra S. | McMahon, Brian J.^;

Affiliations: Arctic Investigations Program, Division of Emerging Infections and Surveillance Services, National Center for Preparedness, Detection and Control of Infectious Diseases, Centers for Disease Control and Prevention, Anchorage, Alaska, USA | Epidemic Intelligence Service, Division of Applied Public Health Training, Epidemiology Program Office, Centers for Disease Control and Prevention (CDC), U.S. Department of Health and Human Services (USDHHS), Atlanta, Georgia, USA | Liver Disease and Hepatitis Program, Alaska Native Tribal Health Consortium, Anchorage, Alaska, USA | Division of Viral Hepatitis, Centers for Disease Control and Prevention (CDC), U.S. Department of Health and Human Services (USDHHS), Atlanta, Georgia, USA

Note: [] Correspondence: Dr. Kathy K. Byrd, M.D., MPH, 1600 Clifton Rd. MS: G-37, 30333, GA, Atlanta, USA. Tel.: +1 404 718 8541; Fax: +1 404 718 8595; E-mail: gdn8@cdc.gov

Abstract: We conducted a 10–15 years follow-up to a long-term prospective cohort study on the immunogenicity of inactivated hepatitis A vaccine in Alaska Native children, who were initially vaccinated between 3–6 years of age. Children received three vaccine doses (320 E.U.) and were randomized into the following vaccination schedules: A (0, 1, 2 months); B (0, 1, 6 months); and C (0, 1, 12 months). Sera were collected every 2 years and tested for hepatitis A virus (anti-HAV). Levels ⩾ 20 mIU/mL were considered protective. Anti-HAV geometric mean concentrations were compared by vaccination schedule at 10, 12 and 14 years of follow-up, using ANOVA. Antibody decline over the entire 15-year follow-up period was also analyzed. While none of the inter-schedule comparisons differed significantly from each other at the 10, 12 and 14-year periods, schedules B and C had significantly higher anti-HAV levels than schedule A over the entire 15 years of the study (P < 0.01). All schedule B and C children maintained seroprotective levels in all follow-up periods. Fourteen percent of schedule A children fell below seroprotective levels at 14 years. Our model estimated that anti-HAV geometric mean concentrations would fall below seroprotective levels at 26, 30 and 32 years for schedules A, B and C, respectively. The data indicate that hepatitis A immunity lasts at least 15 years after vaccination in children and that a booster dose is not needed during that time. However, continued monitoring is necessary to assess the need for a booster dose later in the second and third decade after receipt of the primary series.

Keywords: Hepatitis A, inactivated hepatitis A vaccine, immunogenicity

DOI: 10.3233/JPI-2010-0269

Journal: Journal of Pediatric Infectious Diseases, vol. 5, no. 4, pp. 321-326, 2010