Letters to the Editor

Indian Pediatrics 2002; 39:504-505

Reply

So far IAP is concerned, there is no confusion regarding the schedule. Since there has been a change from the previous schedule, it needed some clarification which was provided in the publication(1). I shall like to clarify the point raised by Dr. Yash Paul, which is relevant.

In vaccination when an antigen is administered, it leads to several responses, e.g., humoral, cell mediated and stimulation of memory cells. Hepatitis B vaccine protects by raising antibody titer to more than 10 IU/ml, which is the protective antibody titer and also act through stimulation of memory cells(2).

It has been observed in several previous studies that the protective antibody level following 3 doses (0,1 and 6 months or 6, 10, 14 weeks or 2, 3, 4 months) persists for a period of atleast 15 years(3). Although the antibody level falls below the protective level after 15 years, there is protective anamnestic antibody response after exposure to hepatitis B virus. This stimulates the memory cells and prevents reinfection by hepatitis B virus. It has also been further noted that some of the individuals who had been infected later on did not develop chronic infection (carrier state) and also were free from development of chronic hepatitis, cirrhosis of liver or hepatocellular carcinoma. In view of this fact, WHO recommends that there is no need of any booster dose of the vaccine (4,6).

WHO has recommended three different schedules e.g., 0, 6 and 14 weeks; 6, 10 and 14 weeks and 0, 6, 10 and 14 weeks. The first schedule starting within 24 hours of birth is recommended in countries where perinatal transmission rate is high. The second option is for countries where perinatal transmission rate is low. The third option suggested by WHO is for ease in administration in the National UIP program where combination vaccine with DPT can be administered at 6, 10 and 14 weeks and monovalent hepatitis B is given at birth. It may be difficult to remember by the health workers to give only DPT vaccine at 10 weeks and combination vaccine at 6 and 14 weeks. Thus, to have uniformity in the National program this 4 dose option has been recommended. This schedule does not produce added benefit raising the antibody titer or booster effect. So far, with the existing scientific knowledge, the three dose schedule suggested by IAP is sufficient unless new information or recommendation emerges.

New Delhi 110 001, India.

1. Dutta AK. IAP Hepatitis B Immunization schedule. Indian Pediatr 2001; 38: 1335-1338.

2. Halder SC, Margolis HS. Hepatitis B immuniza-tion vaccine types, efficacy and indications for immunization. In: Current Topics in Infections Diseases, Vol 12. Eds. Remington JS, Swartz MN. Boston, Blackwey Scientific Publications, 1992; pp 282-308.

3. Harpaz R, Mc Mohan BH, Margolis HS. Elimination of chronic hepatitis B virus infections: Results of the Alaska immunization program. J Infect Dis 2000; 181: 413-418.

4. European Consensus Group on Hepatitis B Immunity. Are booster immunization needed for lifelong hepatitis B Immunity? Lancet 2000; 355: 561-565.

5. Centre for Disease Control. Hepatitis B virus: A comprehensive strategy for eliminating trans-mission in the United States through universal childhood vaccination. Recommendation of the Immunization Practices Advisory Committee. MMWR 1991; 40 (NORR - 13): 1-25.

6. Introduction of Hepatitis B Vaccine Into Childhood Immunization Program. Manage-ment Guidelines, Including Information for Health Workers and Parents. Department of Vaccine and Biologicals. World Health Organization, Geneva, Final draft for comment, February 2001. Website: www.vaccines.WHO. int/vaccines-documents.