Hepatitis B vaccine has an outstanding record of safety, and is considered one of the most effective childhood immunizations. Now, a recent study has revealed that the duration of vaccine protection in children and adults immunized with plasma-derived hepatitis B, lasts for at least 22 years, without requiring booster doses. The study results are published in the latest issue of the Journal of Infectious Diseases.
Brian J McMahon, Scientific Program and Clinical Director of the Liver Disease and Hepatitis Program, Alaska Native Tribal Health Consortium, Alaska, USA, and colleagues, determined the duration of protection offered by plasma-derived hepatitis B vaccine by measuring the antibody levels to hepatitis B surface antigen (anti-HBs). The study also determined the response to a vaccine booster dose. A total of 493 adult Alaska Natives who had received inactivated hepatitis B vaccine at the age of >6 months were tested positive 22 years later. Study participants with anti-HBs levels <10mIU/mL were given an additional dose of recombinant vaccine and evaluated based on antibody titers at 10-14 days, 30-60 days, and 1 year.
The team observed that 298 (60%) participants demonstrated an anti-HBs level of ≥10 mlU/mL, 22 years after primary vaccination. Of the 164 people who received a booster dose, 77% revealed anti-HBs level of ≥10 mlU/mL at 10-14 days, which further increased to 81% by the end of 60 days. The study reported that younger age, peak anti-HBs response after initial vaccination, and the presence of anti-HBs prior to boosting, positively influenced the vaccine booster response. Based on antibody levels and booster dose response, 87% of the total participants were considered to be immune even after 22 years. There was no evidence of acute or long-term chronic hepatitis B infections, suggesting a high level of protection.
Earlier, McMahon et al conducted a 15-year follow-up prospective cohort study (Annuals of Internal Medicine, 2005) in 1,578 Alaska Natives to determine antibody persistence and vaccine protection. The participants were vaccinated with 3 doses of plasma-derived hepatitis B vaccine between 1981 and 1982. Analysis by a longitudinal linear mixed model indicated significantly high anti-HBs levels after 15 years in men vaccinated at an older age with initial anti-HBs titers. The incidence of frequent asymptomatic breakthrough infections was common in participants who did not respond to the vaccine. The findings confirmed that the vaccine provided protection for at least 15 years irrespective of the age group. The study confirmed that the anti-HBs levels dropped significantly after 15 years, in individuals who received primary vaccination at ages 6 months to 4 years.
Previous studies carried out by Chongsrisawat et al (The Southeast Asian Journal of Tropical Medicine and Public Health, 2000) and Floreani et al (Vaccine, 2004) have also demonstrated the long-term persistence of anti-HBs titers in all healthy children and adults receiving the primary vaccine series, respectively. The studies also warded off the need for booster doses after primary immunization in healthy individuals. However, a review by Lu et al (Hepatology, 2004) reported that subsequent booster doses increase the geometric mean titers of anti-HBs, thereby enhancing the protection rate of the primary plasma-derived hepatitis B vaccine. The study revealed a remarkable drop in antibody levels by about 15 years, thus increasing the risk of breakthrough infections.
Hepatitis B vaccine, the first vaccine used across the world against life-threatening liver cancer, is recommended for infants and children by both the American Academy of Pediatrics and the Centers for Disease Control. According to the 2008 statistical report by the WHO, approximately 2 billion people across the world have suffered the hepatitis B infection, with more than 350 million people living with chronic liver infections. Further substantiation of the vaccines’ ability to confer long-term protection mandates the need for adopting universal immunization programs that would help reduce the burden of hepatitis B virus infection.
References
1. McMahon BJ, Dentinger CM, Bruden D, et al. Antibody levels and protection after hepatitis B vaccine: results of a 22-year follow-up study and response to a booster dose. J Infect Dis. 2009 Nov 1;200(9):1390-6.
2. McMahon BJ, Bruden DL, Petersen KM, et al. Antibody levels and protection after hepatitis B vaccination: results of a 15-year follow-up. Ann Intern Med. 2005 Mar 1;142(5):333-41.
3. Chongsrisawat V, Theamboonlers A, Khwanjaipanich S, Owatanapanich S, Sinlaparatsamee S, Poovorawan Y. Humoral immune response following hepatitis B vaccine booster dose in children with and without prior immunization. Southeast Asian J Trop Med Public Health. 2000 Dec;31(4):623-6.
4. Floreani A, Baldo V, Cristofoletti M, et al. Long-term persistence of anti-HBs after vaccination against HBV: an 18 year experience in health care workers. Vaccine. 2004 Jan 26;22(5-6):607-10.
5. Lu CY, Chiang BL, Chi WK, et al. Waning immunity to plasma-derived hepatitis B vaccine and the need for boosters 15 years after neonatal vaccination. Hepatology. 2004 Dec;40(6):1415-20.
