Observational study of vaccine efficacy 14 years after trial of hepatitis B vaccination in Gambian childrenBMJ 2002; 325 doi: https://doi.org/10.1136/bmj.325.7364.569 (Published 14 September 2002) Cite this as: BMJ 2002;325:569
- Hilton Whittle, deputy directora,
- Shabbar Jaffar, senior lecturerb,
- Michael Wansbrough, MSc studentb,
- Maimuna Mendy, senior scientific officera,
- Uga Dumpis, visiting research fellow, Riga Universitya,
- Andrew Collinson, clinical scientista,
- Andrew Hall, professorb
- aMedical Research Council Laboratories, PO Box 273, Banjul, Gambia
- bLondon School of Hygiene and Tropical Medicine, London WC1E 7HT
- Correspondence to: H Whittle
- Accepted 23 April 2002
Objective: To determine the duration of protection from hepatitis B vaccine given in infancy and early childhood.
Design: Cross sectional serological study of hepatitis B virus infection in children of various ages 14 years after the start of a trial of vaccination regimens.
Setting: Two villages in the Gambia.
Participants: Children and adolescents given hepatitis B vaccine in infancy or early childhood: 232 were aged 1-5 years, 225 aged 5-9 years, 220 aged 10-14 years, and 175 aged 15-19 years.
Main outcome measures: Vaccine efficacy against infection and against chronic infection in the different age groups.
Results: Vaccine efficacy against chronic carriage of hepatitis B virus was 94% (95% confidence interval 89% to 97%), which did not vary significantly between the age groups. Efficacy against infection was 80% (76% to 84%). This was significantly lower in the oldest age group (65%, 56 to 73). Of the uninfected participants in this age group, 36% had no detectable hepatitis B virus surface antibody. Time since vaccination and a low peak antibody response were the most powerful risk factors for breakthrough infection (P<0.001 in each case). Low peak antibody response was also a risk factor for chronic carriage (odds ratio 95, 19 to 466).
Conclusions: Children vaccinated in infancy are at increased risk of hepatitis B virus infection in the late teens. The risk of chronic carriage after sexual exposure needs further assessment to determine if booster vaccines are necessary.
Funding Medical Research Council (UK) and Merck Sharpe and Dohme (USA).
Competing interests None declared.