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Immunization Dialogue Indian Pediatrics 2000;37: 904-905 |
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Timing of Booster of Rabies Vaccine |
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The views expressed by Prof. T. Jacob John in this section are personal in nature and should not be construed as the official stand of the Indian Academy of Pediatrics. –Editor-in-Chief
A.K. Sanyal,
1. We must be grateful to Dr. Sanyal for bringing out the discrepancies in our recom-mendations regarding booster immuniza-tion against rabies exposure. As the IAP Textbook of Pediatrics was written by several authors, such discrepancies are possible, but that is no justification for the section editors (myself and Dr. Amdekar) to have failed to identify and correct it. The textbook version is incorrect. To avoid any further ambiguity, let me quote directly from the WHO Recommendations (1997)(1). "Post-exposure treatment of previously vaccinated patients. Patients exposed to rabies who have previously received cell culture or purified duck embryo (not available in India; TJJ) vaccine have the advantage that booster doses of vaccine will rapidly induce a large increase in antibody production (a secondary response), but this treatment is still needed urgently. A short course of a cell culture or purified duck embryo vaccine can be given providing that the patient has previously had a complete pre-or post-exposure course of one of these vaccines, or that rabies neutralizing antibody (>0.5 IU/ml) has been demonstrated at some time in the past no RIG treatment is necessary. Regimen: One injection of vaccine is given on days 0 and 3. The dose is either one standard im dose, which may be 1 ml or 0.5 ml accord-ing to vaccine type, or one intradermal dose. Caution: If antimalarial chemoprophylaxis (e.g., with chloroquine) is being given con-currently, im injections are mandatory. If an id injection does not raise a satisfactory papule (see procedure), a second id injection should be given in opposite arm."(1) What I had done was to modify the above recommendation a little bit. In our situation, documentation is weak, often absent, So, we rely on past history of immunization by asking questions and expect accurate answers. With time, people forget the number of doses or the nature of vaccine taken previously. For these reasons I had recommended the 2 dose booster for 5 to 10 years after the full pre-or post-exposure immunization and 3 doses for upto 20 years. Contrary to what Dr. Sanyal understood, the days recommended by the WHO and by me are one and the same, namely days 0 and 3 (not days 0 and 7)(2). When 3 doses are given the timing is on days 0, 3 and 7(2). 2. The second question is based on some misunderstanding. HDCV is one cell culture vaccine, others being chick embryo fibroblast based or Vero cell based. All these and the Swiss duck egg grown and purified vaccine are equal in efficacy and safety. So all of them can be treated on par. In all cases antibody response starts early, and can be demonstrated by day 7 in most cases and by day 10 or 14 in all cases, irrespective of which vaccine is being used. Passive immunization is for immediate protection, within minutes of giving the preformed antibodies. In cases in which passive immunization is necessary, but rabies immune globulin (RIG, human or equine) is not avail-able, we must at least try to use a schedule that induces very early immune response. For this purpose, the 2-1-1 im schedule or the 8 site id schedule may be used. The former consists of 2 doses of a cell culture vaccine on day 0 and one dose each on days 7 and 21(1). The other consists of 8 id inoculations of 0.1 ml of HDCV or chick embryo cell vaccine at different body sites on day 0, followed by 4 such inoculations on day 7 and one each on days 28 and 90(1). From the technical point of view, the doctor must record the need for passive immunization and also the lack of availability of the RIG, if the method adopted is to be found acceptable in the eyes of peers, in case of litigation.
T. Jacob John,
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