There are more than two billion individuals with serological evidence of hepatitis B infection worldwide. Of these, 400 million are chronic carriers and 500,000 to 1.2 million will die annually from cirrhosis and hepatocellular carcinoma [1,2]. Despite advances in antiviral therapy, only a minority of patients with chronic hepatitis B will have a sustained response. Thus, primary prevention by vaccination to increase herd immunity remains the main thrust in the control of hepatitis B virus (HBV) infection.
Currently available hepatitis B vaccines are extremely safe and have an efficacy of >90 percent and are effective against all HBV serotypes and genotypes. Thus, HBV infection can potentially be eradicated through global vaccination.
In its effort to eradicate chronic hepatitis B infection, the World Health Organization (WHO) advocates HBV vaccination. The vaccination coverage is currently measured only after the completion of the third dose of vaccine (HepB3). Globally, the HepB3 rate has increased from 3 percent in 1992 to 75 percent in 2010 . In the United States, the vaccine coverage among adults is low, decreasing from 58 percent for those between 18 and 20 years old to 26 percent for those between 41 and 49 years old .
Despite this suboptimal vaccine coverage, the incidence of acute hepatitis B has decreased by 75 percent (from 8.5/100,000 in 1990 to 2.5/100,000 in 2004). The biggest decline in incidence was seen in children and adolescents . Even in countries that actively advocate universal vaccination, coverage is less than 100 percent. As an example, the vaccine coverage in Taiwan as of 2004 was >90 percent for children younger than 14 years of age but only between 87 to 90 percent among teenagers between 15 and 17 years of age .
Vaccine coverage is not uniform globally. Coverage in the Eastern Mediterranean, Western Pacific, and America exceed 80 percent, while the HepB3 coverage rate for Europe and Africa is 75 percent. Unfortunately, in areas of high prevalence like South-East Asia, the coverage remains low at approximately 50 percent.