The risk of perinatal hepatitis B virus transmission: hepatitis B e antigen (HBeAg) prevalence estimates for all world regions

Background: HBeAg presence in childbearing-age women is a major determinant of perinatal hepatitis B virus (HBV) transmission. The risk of developing chronic HBV infection and liver disease is highest at young age. Our aim was to assess perinatal HBV transmission risk by means of estimating age- and region-specific HBeAg prevalence. Methods: Based on observed HBeAg seroprevalence data obtained from a systematic literature review, we modeled HBeAg prevalence using an empirical Bayesian hierarchical model. Age- and region-specific estimates were generated for 1990 and 2005. Results: Globally, highest HBeAg prevalence of over 50% was found in 0-9 years old girls. At reproductive age, HBeAg prevalence was 20-50%. Prevalence was highest in young females in East Asia in 1990 (78%), the infection was less common in Sub-Saharan and North Africa. Regional differences in prevalence were smaller in 2005. There was an overall decrease in HBeAg between 1990 and 2005, which was strongest among girls in Oceania (23.3% decline), South and South-East Asia (14% decline). However, in these regions, prevalence remained high at 67% among young females in 2005. Smaller decreases were observed in women at reproductive age, at which 24-32% of all HBsAg-positive women were HBeAg-positive in 2005, with lowest prevalence in Southern Sub-Saharan Africa and highest prevalence in Oceania and South-East Asia. Conclusions: HBeAg estimates are crucial for understanding the epidemiology of HBV and for prioritizing implementation of WHO's prevention recommendations for all infants to receive the first dose of hepatitis B vaccine within 24 hours of birth. Results will have importance as access to treatment for chronic HBV infection is expanded.