Low level of Hepatitis B virus infection in children 20 years after initiation of infant vaccination program in Wallis and Futuna

Abstract

The prevalence of hepatitis B virus (HBV) in Wallis and Futuna (WAF) was one of the highest in the Pacific and was the driving factor for introducing hepatitis B (HepB) vaccination in 1992 and HepB birth dose (HepB-BD) in 2006. Using lymphatic filariasis (LF) transmission assessment survey (TAS) as a survey platform for eliminating LF, we assessed HBV surface antigen (HBsAg) seroprevalence, HepB vaccination coverage, and its timeliness among schoolchildren in WAF. From one finger prick of all registered fourth and fifth grade students, we tested HBsAg and filariasis antigen simultaneously, and estimated HepB vaccination coverage and timeliness by reviewing students' immunization cards. Since the children targeted were born when the three-dose HepB schedule was 2, 3, and 8 months, we defined timely vaccination if each dose was given by 3, 4, and 12 months. Of 476 targeted, 427 were enrolled. HBsAg prevalence was 0.9%. Estimated HepB vaccination coverage was 97%, 97%, and 96% for the first, second, and third doses, respectively, yielding coverage for all three doses of 96%. Proportion of timely vaccination was lower: 80%, 56%, and 65%, respectively, and less than 50% for all three doses combined. The seroprevalence of HBsAg among schoolchildren in WAF is less than 1%, close to the control goal. HepB vaccination coverage was high, but many children were vaccinated late. We recommend increasing the efforts for timely HepB vaccination. By combining an HBV seroprevalence survey and coverage assessment, we demonstrated the benefit of using TAS as a public health platform to access schoolchildren.