Active immunization protects the unexposed population from HBV infection. Screening of blood donors for HBsAg and the global implementation of prophylaxis have significantly reduced the incidence of nosocomial infections. Concurrent HBV DNA testing during screening can further reduce transfusion-associated disease transmission, but the attendant increased cost limits its use.
Instructing patients to prevent transmission, implementing screening and vaccination for high-risk groups, and implementing universal vaccination for newborns are important measures to prevent HBV transmission and reduce its global disease burden.
Safe and effective vaccines against HBV have been available since 1981, mostly recombinant DNA vaccines expressing only HBsAg. In addition to monovalent vaccines, there are now combination vaccines that also target HAV, as well as combination vaccines against diphtheria, tetanus, and Haemophilus influenzae type B. Until the end of 2011, 180 countries had included HBV vaccines in their childhood immunization programs.
Up to 90% of acute HBV infections in newborns are chronic, so interrupting mother-to-child transmission of HBV is critical. Mothers with high HBV DNA quantification (>107 copies/ml) are at some risk of neonatal infection, even with passive immunostimulants combined with immunoglobulin and hepatitis B vaccine. Antiviral therapy given in the third trimester may further reduce the risk of mother-to-child transmission.
In summary – indications for HBV vaccine.
1. All newborns
2. All children and adolescents who were not vaccinated at birth
3.Adults at high risk
(1) Gay men
(2) Those with multiple sexual partners
(3) People with intravenous addiction
(4) Hemodialysis patients
(5) Social admission structure personnel
(6) Health workers and public safety workers
(7) Spouses, sexual partners and family members of persons with HBV virus
Newborns of virus-carrying mothers who also need to be given immunoglobulin
The above lists the recommended groups for HBV vaccination. In immunocompetent individuals, approximately 95% of the population will achieve a response to the vaccine, i.e., anti-HBs potency >10 mIU/ml, with an expected duration of protection of 15 years or more. The anti-HBs potency decreases over time. However, for vaccinated populations, rare or rare symptomatic acute and chronic infections are seen, suggesting the presence of immune memory.
WHO issued an opinion letter signed by the Committee on Prevention of Viral Hepatitis in 2009 stating that there is no conclusive evidence to confirm the need for booster injections outside of scheduled immunization. Data from Taiwan show that a significant proportion of people lose immune memory for HBsAg 15 years or more after vaccination.
The HBV vaccine is fairly safe, its association with multiple sclerosis and autism has not been fully confirmed, and current vaccines are thimerosal-free. Although the need for booster injections is controversial, it should be reasonable to implement booster vaccination in high-risk groups, given the high safety profile of the vaccine.
The introduction of HBV vaccine has brought about a decrease in the incidence of liver cancer in addition to a decrease in the incidence of HBV infection. In Taiwan, the prevalence of HBsAg carriage in children decreased from 10% in 1984 to 0.5% in 2009, and the incidence of hepatocellular carcinoma in children and adolescents also decreased by 70%.
In the United States, the incidence of acute HBV infection declined by 81% between 1990 and 2006, and the overall HBsAg carriage rate declined from 0.38% to 0.27%, but this decline was concentrated in children and adolescents, while the carriage rate in adults remained relatively stable, which may be related to migration from chronically infected populations in disease-endemic countries.
Forty-seven European countries have adopted universal HBV vaccination programs with similar reported infection rates. 6 low-prevalence European countries (Denmark, Finland, Iceland, Norway, Sweden, and the United Kingdom) have adopted targeted vaccination strategies, with vaccination of only high-risk populations. For these countries, horizontal and sexual transmission from immigrant groups is the main problem.