A cohort study to evaluate persistence of hepatitis B immunogenicity after administration of hexavalent vaccines
In 2001, two hexavalent vaccines were licensed in Italy (Hexavac(R), Infanrix Hexa(R)), and since 2002 were extensively used for primary immunization in the first year of life (at 3, 5, 11/12 months of age). In 2005, the market authorization of Hexavac(R) was precautionary suspended by EMEA, because of doubts on long-term protection against hepatitis B virus.
The objectives of this study were to evaluate the persistence of antibodies to anti-HBs, in children in the third year of life, and to investigate the response to a booster dose of hepatitis B vaccine.
Methods: Participant children were enrolled concomitantly with the offering of anti-polio booster dose, in the third year of life. Anti-HBs titers were determined on capillary blood samples.
A booster dose of hepatitis B vaccine was administered to children with anti-HBs titers <10 mIU/ml, with the monovalent precursor product of the previously received hexavalent vaccine. HBsAb titers were tested again one month after the booster.
Results: Sera from 113 children previously vaccinated with Hexavac(R), and from 124 vaccinated with Infanrix Hexa(R) were tested for anti-HBs.
Titers were [greater than or equal to]10 mIU/ml in 69% and 96% (p<0,0001) respectively. The proportion of children with titers [greater than or equal to]100 mIU/ml did also significantly differ among groups (27% and 78%; p<0,0001).
Post-booster, 93% of children achieved titers [greater than or equal to]10 mIU/ml, with no significant difference by vaccine group.DiscussionFifteen months after third dose administration, a significant difference in anti-HBs titers was noted in the two vaccine groups considered. Monovalent hepatitis B vaccine administration in 3-year old children induced a proper booster response, confirming that immunologic memory persists in children with anti-HBs titers <10 mIU/ml.
However, long-term persistence of HBV protection after hexavalent vaccines administration should be further evaluated over time.
Author: Cristina Giambi, Antonino Bella, Antonella Barale, Domenico Montu, Maria Marchisio, Maurizio Oddone, Salvatore Zito, Maria Rapicetta, Paola Chionne, Elisabetta Madonna and Marta L Ciofi degli Atti
Credits/Source: BMC Infectious Diseases 2008, 8
Published on: 2008-07-28
Copyright by the authors listed above - made available via BioMedCentral (Open Access). Please
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