Publication: Efficacy and effectiveness of infant vaccination against chronic hepatitis B in the Gambia Hepatitis Intervention Study (1986-90) and in the nationwide immunisation program
Accepted Date
2014-01-04
Issued Date
2014-01-07
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Language
eng
ISSN
1471-2334 (electronic)
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Mahidol University
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BioMed Central
Bibliographic Citation
Peto TJ, Mendy ME, Lowe Y, Webb EL, Whittle HC, Hall AJ. Efficacy and effectiveness of infant vaccination against chronic hepatitis B in the Gambia Hepatitis Intervention Study (1986-90) and in the nationwide immunisation program. BMC Infect Dis. 2014 Jan 7;14:7.
Suggested Citation
Peto, Thomas J., Mendy, Maimuma E., Lowe, Yamundow, Webb, Emily, Whittle, Hilton C., Hall, Andrew J Efficacy and effectiveness of infant vaccination against chronic hepatitis B in the Gambia Hepatitis Intervention Study (1986-90) and in the nationwide immunisation program. Peto TJ, Mendy ME, Lowe Y, Webb EL, Whittle HC, Hall AJ. Efficacy and effectiveness of infant vaccination against chronic hepatitis B in the Gambia Hepatitis Intervention Study (1986-90) and in the nationwide immunisation program. BMC Infect Dis. 2014 Jan 7;14:7.. doi:10.1186/1471-2334-14-7. Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/684
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Title
Efficacy and effectiveness of infant vaccination against chronic hepatitis B in the Gambia Hepatitis Intervention Study (1986-90) and in the nationwide immunisation program
Corresponding Author(s)
Abstract
BACKGROUND: Gambian infants were not routinely vaccinated against hepatitis B
virus (HBV) before 1986. During 1986-90 the Gambia Hepatitis Intervention Study
(GHIS) allocated 125,000 infants, by area, to vaccination or not and thereafter
all infants were offered the vaccine through the nationwide immunisation
programme. We report HBV serology from samples of GHIS vaccinees and unvaccinated
controls, and from children born later.
METHODS: During 2007-08, 2670 young adults born during the GHIS (1986-90) were
recruited from 80 randomly selected villages and four townships. Only 28%
(753/2670) could be definitively linked to their infant HBV vaccination records
(255 fully vaccinated, 23 partially vaccinated [1-2 doses], 475 not vaccinated).
All were tested for current HBV infection (HBV surface antigen [HBsAg]) and, if
HBsAg-negative, evidence of past infection (HBV core-protein antibody
[anti-HBc]). HBsAg-positive samples (each with two age- and sex-matched
HBsAg-negative samples) underwent liver function tests. In addition, 4613
children born since nationwide vaccination (in 1990-2007) were tested for HBsAg.
Statistical analyses ignore clustering.
RESULTS: Comparing fully vaccinated vs unvaccinated GHIS participants, current
HBV infection was 0.8% (2/255) vs 12.4% (59/475), p < 0.0001, suggesting 94% (95%
CI 77-99%) vaccine efficacy. Among unvaccinated individuals, the prevalence was
higher in males (p = 0.015) and in rural areas (p = 0.009), but adjustment for
this did not affect estimated vaccine efficacy. Comparing fully vaccinated vs
unvaccinated participants, anti-HBc was 27.4% (70/255) vs 56.0% (267/475), p <
0.00001. Chronic active hepatitis was not common: the proportion of
HBsAg-positive subjects with abnormal liver function tests (ALT > 2 ULN) was
4.1%, compared with 0.2% in those HBsAg-negative. The prevalence of antibodies to
hepatitis C virus was low (0.5%, 13/2592). In children born after the end of
GHIS, HBsAg prevalence has remained low; 1.4% (15/1103) in those born between
1990-97, and 0.3% (9/35150) in those born between 1998-2007.
CONCLUSIONS: Infant HBV vaccination achieves substantial protection against
chronic carriage in early adulthood, even though approximately a quarter of
vaccinated young adults have been infected. This protection persists past the
potential onset of sexual activity, reinforcing previous GHIS findings of
protection during childhood and suggesting no need for a booster dose. Nationwide
infant HBV vaccination is controlling chronic infection remarkably effectively.