Investigators from Gambia and England determined the duration of protection from hepatitis B vaccine given in infancy and early childhood.
A total of 852 children and adolescents from 2 villages in the Gambia, who were given hepatitis B vaccine in infancy or early childhood, were included in the study.
The research was initiated 14 years after the start of a trial of hepatitis B vaccination regimens.
Of the participants, 232 were aged 1-5 years, 225 aged 5-9 years, 220 aged 10-14 years, and 175 aged 15-19 years.
The researchers measured vaccine efficacy against infection and against chronic infection in the different age groups.
|Risk factors for breakthrough infection:|
- Time since vaccination
- Low peak antibody response
| British Medical Journal |
Vaccine efficacy against chronic carriage of hepatitis B virus was 94%, which did not vary significantly between the age groups.
Efficacy against infection was 80%. This was found to be significantly lower in the oldest age group (65%).
The team found that, 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.
Low peak antibody response was also a risk factor for chronic carriage (odds ratio 95).
Hilton Whittle, of the Medical Research Council Laboratories, Banjul, Gambia, said on behalf of fellow authors, "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," it was concluded.