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Mayorga, O.* ; Bühler, S.* ; Jaeger, V.K.* ; Bally, S.* ; Hatz, C.* ; Frösner, G. ; Protzer, U. ; van Damme, P.* ; Egger, M.* ; Herzog, C.*

Single-dose Hepatitis A immunization: 7.5-year observational pilot study in nicaraguan children to assess protective effectiveness and humoral immune memory response.

J. Infect. Dis. 214, 1498-1506 (2016)
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BACKGROUND:  Universal 2-dose hepatitis A virus (HAV) vaccination of toddlers effectively controls hepatitis A. High vaccine costs, however, impede implementation in endemic countries. To test single-dose vaccination as a possible alternative, we initiated an observational, longitudinal study in Nicaragua, to assess protective effectiveness and-through challenge vaccination-humoral immune memory response. METHODS:  After a 2003 serosurvey, 130 originally seronegative children received one dose of virosomal HAV vaccine in 2005, followed by yearly serological and clinical assessments until 2012. After 7.5 years, a vaccine booster was administered. Concurrent antibody screening of patients presenting with hepatitis symptoms documented persistent HAV circulation in the communities studied. RESULTS:  Between serosurvey and vaccination, 25 children contracted hepatitis A subclinically (>8000 mIU/mL anti-HAV). In the remaining 105 children, immunization resulted in anti-HAV levels of 17-572 mIU/mL. Based on the ≥15% annual infection risk, an estimated 60% of children were exposed to HAV encounters during follow-up. No child presented with hepatitis symptoms. Serological breakthrough infection (7106 mIU/mL) was documented in 1 child, representing an estimated protective effectiveness of 98.3% (95% confidence interval, 87.9-99.8). Boosting elicited an average 29.7-fold increase of anti-HAV levels. CONCLUSIONS:  In children living in hyperendemic settings, a single dose of virosomal HAV vaccine is sufficient to activate immune memory and may provide long-term protection.
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Publication type Article: Journal article
Document type Scientific Article
Corresponding Author
Keywords booster interval; children; hepatitis A; hepatitis A vaccine; immune memory; long-term follow-up; protective effectiveness; single-dose vaccination
ISSN (print) / ISBN 0022-1899
e-ISSN 1537-6613
Journal Journal of Infectious Diseases, The
Quellenangaben Volume: 214, Issue: 10, Pages: 1498-1506 Article Number: , Supplement: ,
Publisher Oxford University Press
Non-patent literature Publications
Reviewing status Peer reviewed
Institute(s) Institute of Virology (VIRO)