TechNet-21 - Forum

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  1. Omesh K. Bharti
  2. Programme management
  3. Thursday, 06 November 2014
An Editorial in Indian Pediatrics the journal of the Indian Academy of Pediatrics has again raised doubts about the usefulness of Hepatitis-B vaccination in India. Results of the pilot study launched in Andhra Pradesh to evaluate the usefulness of the vaccine have been published in the latest issue of Indian Pediatrics. In an accompanying editorial Rajeev Kumar and Jacob Puliyel of the Department of Paediatrics at St. Stephens Hospital say the results are clear evidence that the vaccine has not been very useful. "If the findings of this study are replicated in other areas, it should prompt a re-evaluation of the need for this vaccine in the immunization programme of the country" the editorial says. Twelve years ago the Global Alliance on Vaccines and Immunization (GAVI) provided India with Rs.271.9 million to study Hepatitis B vaccination in India. No study of efficacy was undertaken and universal immunization was introduced in a phased manner. Hepatitis B spreads like AIDS from mother to child or from person to person through contaminated needles or sexual contact. However unlike AIDS, the majority of those who get infected with Hepatitis B clear the organism from their bodies. A few however do not clear the virus and become chronic carriers. Some chronic carriers develop liver cancers or cirrhosis of the liver, 40 years later. Vaccination is meant to reduce the numbers who become chronic carriers and long term problems. The pilot study in rural Andhra Pradesh looked at over 2500 children who were given the vaccine against a similar number who had not received the vaccine and used as control group. The study found that the incidence of chronic carriers was similar, regardless of vaccination status or, in other words, "the vaccination did not reduce hepatitis B carrier rate," defeating the primary aim of the immunization programme, the editorial says. Protective levels of antibodies fell rapidly among the vaccinated and by 11 years only 13% were protected. On the other hand among those not vaccinated, 33% had developed natural immunity by 6 years of age. Kumar and Puliyel note that Hepatitis-B vaccine in now being given as Pentavalent vaccine in combination with DPT and Hib (Haemophilus influenzae type B) vaccines. They say that the efficacy of Hepatitis-B vaccine when given mixed with other vaccines "is likely to be even lower than what was reported in the study that was conducted with Hepatitis-B as a stand-alone vaccine." The link below for full article: http://www.indianpediatrics.net/nov2014/870.pdf
Omesh K. Bharti Accepted Answer
1. What is the assumption on Table 1 mislabeling, What would the corrected Table 1 look like? 2. Please donot forget that the purpose of immunization is to reduce chronic carriers (HBsAg) who we assume could have long term consequences. This rate was 0.15% and 0.17% and there was no difference between those vaccinated and those not vaccinated. That is why the vaccine is said to be not of a value for universal immunization for the cost benefit reson therefore only high risk populations should have been the focus of vaccination strategy. The fact that the study was not powered to look for such tiny differences is not pertinent. 3. What do we mean "anti-HBs antibody was 10-fold higher than anti-HBc." The antibody titre in individual children is not provided so how do authors say antibody is 10 fold higher? It is not expected for each rise mIU/ml of anti-HBs there would of exactly similar mIU/ml rise in anti-HBc when the un-vaccinated get natural disease. I assume they mean that 18% of un-vaccinated had HBs antibody but only 1.8% had HBc antibody (thereby implying the 1.8% of the unvaccinated got HBs antibody with natural infection and the remaining 16.2% had got antibody by vaccination) ! Is there any study that shows that that antibody to surface antigen will persist for exactly the same duration as antibody to core antigen after natural disease? All these are assumptions that are made . The fact remains that the incidence of chronic carrier rate is very low and there is no fall with immunization suggesting the vaccine wasnot worth the expenditure and for the purpose for which it was given, in this population. Still I expect a healthy debate o correct the either side scientifically. Regards, Omesh Bharti
  1. more than a month ago
  2. Programme management
  3. # 1
Karen Hennessey Accepted Answer
The paper published in the most recent issue of Indian Pediatrics (Aggarwal et al) was reviewed by us. The interpretation of the results of the study were rendered difficult because of the apparent mislabelling on the rows in Table 1 of the paper. If one assumes that this table was improperly labelled and that the data presented in the text, which are also consistent with those in Table 2, are correct, our interpretation would be similar to the conclusions drawn by the authors of the paper. The study was designed to measure a decrease of HBsAg prevalence from an estimated 3% in unimmunized children to 1% among immunized children. The authors found a much lower prevalence in both immunized and unimmunized children (0.15% and 0.17%, respectively) and, hence, the study lacked sufficient statistical power to measure any significant difference between the two groups. In addition, and more importantly, the prevalence of anti-HBs antibody was close to 10-fold higher than anti-HBc among unimmunized children. The presence of anti-HBs in the absence of anti-HBc occurs as a result of vaccination. Hence, the authors have rightly concluded that a large proportion of those classified as “unimmunized” in this study were wrongly classified and may have received vaccine outside the national immunization programme. As such, it is difficult to draw any conclusions on the effectiveness of the vaccine based on these data. The fact that the prevalence of anti-HBc was lower among immunized children, compared to unimmunized children suggests that vaccination did have an effect on the prevalence of natural infection, though because of the misclassification the true effectiveness of vaccination is difficult to assess. It is also important to note that the antibody measurements were made 7 to 9 years after vaccination. As noted by the authors, antibody levels are known to decline and will be lower than the high rates (close to 95%) observed immediately following vaccination. However, available data show that even in the absence of measurable antibody the risk of chronic infection is very low in immunized individuals. Available data also show that the immune response to hepatitis B vaccine when given as a combination vaccine is comparable to the that of the individual vaccines. The licensure of combination vaccines is based on demonstration of non-inferiority of the response to the individual vaccines in the combination. Karen Hennessey Thomas Cherian Disclaimer: The authors are staff members of the World Health Organization. The authors alone are responsible for the views expressed in this posting and they do not necessarily represent the decisions or policies of the World Health Organization.
  1. more than a month ago
  2. Programme management
  3. # 2


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