African children 15 to 17 years of age demonstrate significantly reduced hepatitis B vaccine sero-protection rates: evidence from a systematic review and meta-analysis
Authors: Muwanda Fahad , Sendagire Hakim , Mboowa Gerald , Kateete David Patrick , Achan Beatrice , Mupere Ezekiel , Kafeero Hussein Mukasa , Bagaya Bernard Ssentalo 
Published: November 2022

Background
Childhood HBV immunization remains globally fundamental to the elimination of hepatitis B virus (HBV). However the African paediatric HBV vaccine sero-protection rates and their determinants are crucial to establish; as they remain inconclusively studied. We sought to verify the extent of immune protection accorded by HBV vaccine to African children up to 17 years and probable associated factors. To that effect, we pooled the prevalence of HBV vaccine sero-protection rates from a vast array of primary studies conducted in the Northern, Western and Southern Africa regions. We attained articles published from 1999 to 2021; by searching Google Scholar, Willey library, African Journals Online (AJOL), EMBASE, Scopus, and PubMed electronic databases. We included studies that investigated the sero-protection rates accorded by HBV vaccine among childhood recipients under 15, and 15 to 17 years in Africa, published in English and in peer reviewed journals. Pooled prevalence was used to determine HBV vaccine sero-protection rates. This study is registered with PROSPERO under the registration number CRD42022361277.
Results
A significantly higher (p < 0.0001) HBV vaccine sero-protection rate was indicated among children under 15 years of age (69.07%) than children 15 to 17 years (32.368%), 95% CI = [34.2454–39.0847%]. Additionally, children under 15 years from the Southern Africa region demonstrated significantly higher HBV sero-protection rates (85.221%, p < 0.0001) than their counterparts in the Northern (64.242%, p < 0.0001) and Western Africa (70.566%, p < 0.0001), CI = [18.312–23.5317%]. Conversely, children 15 to 17 years of age from the Western Africa region demonstrated a low but higher HBV vaccine sero-protection rate (38.704%, p < 0.0001) than those from the Northern Africa region (26.253%, p < 0.0001), CI = [9.7793–15.0838%]. However, studies for children under 15 years; that were published between 1999 and 2012, and those published between 2016 and 2021 were comparable with HBV vaccine sero-protection rates of 67.421% and 71.475 respectively, p < 0.0013, CI = [1.5894–6.5158%]. On the contrary, studies for children 15 to 17 years; that were published between 2015 and 2016 showed low but significantly higher HBV vaccine sero-protection rates (26.253%,%, p < 0.0001), than studies published between 2002 and 2013 (4.306%, p < 0.0001), CI = [19.8746–24.03%].
Conclusion
Whereas successful integration of the commendably efficacious HBV vaccine on the extended programs on immunizations (EPI) has been a major achievement in the eradication of HBV infection in Africa, markedly reduced HBV vaccine sero-protection rates are persistently demonstrated among adolescent children 15 to 17 years of age. Future EPI evaluation studies need to supplement and augment our findings, and perhaps establish and clarify the need for booster dose vaccination, particularly in the most at risk pediatric African populations.