Hepatitis B serologic survey and review of immunization records of children, adolescents and adults in Fiji, 2008–2009

Abstract

BackgroundIn Fiji, hepatitis B (HB) vaccine was introduced into childhood immunization program in 1989 and has been administered as a pentavalent since 2006. This study aimed to: (i) survey and examine the extent to which HB infection continue to occur in children, adolescents and adults in Fiji, and (ii) determine HB coverage rates and timeliness of vaccine administration to children.MethodsSerum samples of children, adolescents and adults (aged 6 months to <5 years, 16–20 years, and 21–49 years, respectively) collected between 2008–2009 were tested for serologic markers of HB virus infection namely, HB surface antigen (HBsAg), anti-HBs and anti-HB core antigen (anti-HBc). Health record card of each child was reviewed.ResultsNone of the participating children (0/432) was positive for HBsAg. Overall prevalence of HBsAg among adolescents and adults was 5.6% (7/124) and 3.2% (12/370), respectively. High prevalence (98.1%) of anti-HBs was observed in children. An estimated 17.4% of adolescents and adults had evidence of past HBV infection (anti-HBc positive), of which 87.2% recovered from infection but the remaining 12.8% developed chronic infection. Percentage of children who completed at least 3 doses of HB immunization was 99.3%, and who received them on schedule was 58.5%.ConclusionAlthough sample populations for this study is less robust compared to 1998, the prevalence of HBsAg and anti-HBc in children and adults before and after the implementation of the immunization program is much lower. The findings are a positive step in showing that Fiji’s HB vaccine control program is achieving its objectives.

Long-term impact of infant immunization on hepatitis B prevalence: a systematic review and meta-analysis

“…The prevalence of HBsAg in the corresponding no vaccination cohorts were substantially higher, ranging from 0.6% 48 to 16.3% 34 (median: 9.8%). All except one study 45 reported a decrease in HBsAg prevalence; the combined RP in vaccinated populations was 0.24 (95% CI: 0.16–0.35; Fig. 2 ).…”

“…Restricting analyses to those with HBsAg prevalence under 10% in the unvaccinated group yielded 10 studies, all of which assessed HBsAg positivity in cohorts with universal vaccination. 29 , 30 , 36 – 40 , 45 , 47 , 48 The combined RP was 0.34 (95% CI: 0.23–0.52). In comparison, RP was 0.17 (95% CI: 0.12–0.25) across the 11 studies with HBsAg prevalence of at least 10% in the unvaccinated cohort.…”

“…Of the 26 studies that met the inclusion criteria ( Table 1 ) 21 , 24 – 48 most were from Taiwan, China (14 articles), 21 , 24 – 26 , 28 , 29 , 31 – 35 , 37 , 39 , 47 six from mainland China, 36 , 40 , 41 , 44 , 46 , 48 two each from the Gambia 30 , 43 and Italy, 27 , 42 and one each from Australia 38 and Fiji. 45 The number of study participants aged 15 years or older varied substantially, from 259 37 to 738 195 40 (median: 3776). Eleven studies included both targeted and universal vaccination cohorts, 21 , 28 , 29 , 31 , 32 , 34 , 35 , 37 – 39 , 47 four studies included a targeted vaccination cohort only, 24 – 26 , 41 while 11 studies had only a universal vaccination cohort.…”

“…Twenty studies used a single cross-sectional seroprevalence survey design, 23 , 25 , 26 , 28 – 31 , 33 – 42 , 44 , 45 , 47 , 48 four involved two or more cross-sectional seroprevalence survey time points 21 , 24 , 27 , 32 and two were per-protocol analyses of a cluster randomized trial. 43 , 46 Participants included university entrants, 21 , 25 ,26.47, 35 , 44 high-school students, 24 women giving birth, 31 , 38 blood donors, 48 clinic attendees seeking a health check-up, 33 hospital outpatients, 42 members of population-based cohorts 27 , 30 , 37 , 41 , 43 , 46 and participants in health screening.…”

“…Five studies used self-reporting, and found coverage ranging from 55.9% (7 700 of 13 765 people) to over 98% (872/878 people). 25 , 28 , 36 , 37 , 45 Two cohort studies were able to verify the vaccination status of the entire vaccinated group. 30 , 43 One study reported 76.1% (842/1107 people) coverage of the third vaccine dose overall, but 34.5% (35/99 people) for those older than 15 years in the universal vaccination cohort and 19.0.% (10/53 people) in the targeted vaccination cohort.…”