Most countries experienced decreases in hepatitis B surface antigen (HBsAg) prevalence, according to a study published in the Journal of Hepatology.1
Researchers at the Helmholtz Centre for Infection Research in Braunschweig, Germany reviewed data from published systematic review on chronic hepatitis B virus (HBV) prevalence. They analyzed countries categorized into world regions according to the definition of the World Health Organization (WHO). In order to ensure stability of analyzed time trends, researchers chose to only include those countries for which HBsAg data was available for 10 separate time points between 1957 and 2013. HBsAg relative changes were defined as follows: +/-2% as small, +/- 5% as medium, and > 5% as strong.
The “strongest relative reductions in prevalence between 11% and 12% per year occurred in the Democratic Republic of the Congo, Brazil, China, and Malaysia” and “the greatest relative increases in Papua New Guinea,” the researchers noted.
The European region revealed 4 different patterns. “There were those countries indicating a constantly high or increasing prevalence like Russia, Poland, and Romania. High income countries of Western Europe, on the other hand, had constantly low prevalence whereas countries of former high HBV endemicity like Turkey and Albania showed medium decreases in recent years. Furthermore, we found very strong declines in Mediterranean countries like Greece,” said Rafael Mikolajczyk, MD, co-author of the study, in a press release to Helmholtz Centre for Infection Research.2
In Africa, some countries demonstrated no change in prevalence; increases were seen in Uganda (odds ratio [OR] 1.05 per year; 95% confidence interval [CI] 1.04-1.06), Nigeria (OR 1.02; 95% CI, 1.02-1.02), Senegal (OR 1.01; 95% CI, 1.01-1.02), and South Africa (OR 1.02; 95% CI, 1.01-1.02).
The countries analyzed in the study were noted by researchers to have periods of low HBV vaccine coverage around 1995 and it was hypothesized that a period of “catch-up vaccinations” may be an underlying cause for the noted reduction in HBsAG prevalence. “However, given the risk of developing chronic HBV being strongly dependent on age at infection, the effects of catch-up vaccinations in older ages might not be fully reflected in data from surveys reporting chronic HBV carriage but rather in reports on acute hepatitis B cases,” the researchers reported.
The findings of this study were mainly limited by quality and frequency of the data made available to researchers for analysis during the time period analyzed.
“The extent to which decreases are attributable to preventive interventions, for example HBV vaccination, varies by country and depends on time of vaccine implementation and coverage,” said Dr Ott in the journal article’s accompanying press release. Implementing the prevention and control recommendations of the WHO by administering HBV vaccination at birth to prevent early childhood transmission of HBV can further help to decrease transmission in adulthood.
- Ott JJ, Horn J, Krause G, Mikolajczyk RT. Time trends of chronic HBV infection over prior decades – a global analysis. J Hepatol. 2016. doi: 10.1016/j.jhep.2016.08.013.
- Epidemiologic Study Reveals Worldwide Decreases in Chronic HBV Infection [press release]. Braunschweig, Germany: Helmholtz Centre for Infection Research; October 3, 2016.