There is a simplified method of administering rabies vaccines that is economical and just as effective at stimulating anti-rabies antibodies as the more expensive, standard vaccine regimen, according to an article published on April 23, 2008 in the open access journal PLoS Neglected Tropical Diseases.

Deaths from rabies in humans are all the result of failure to administer adequate prophylaxis. After being bitten by a rabid animal, it is essential that the wound be cleaned immediately, and that rabies vaccines and injections of anti-rabies antibody be administered to effectively block fatal infections.

Current vaccines have been approved by the World Heath Organization and administered intramuscularly, but are prohibitively expensive, making them difficult to obtain in developing countries. However, anti-rabies immunoglobulin is difficult to obtain in developing countries, so prevention depends on effective vaccine treatment for people who are bitten. For instance, in Africa, the average cost of an intramuscular course of vaccine is $39.60 USD, which is the equivalent of 50 days’ wages in that area.

The are two more economical vaccine regimens, which involve the injection of small amounts of the vaccine intradermally at two or eight sites on the first day of the course. In the eight shot method, a larger dose is used, thus requiring only one initial day of shots; with the two shot method, two administration days are necessary. Subsequent booster shots, available in several locations, complete the vaccination. While these methods are economically more viable in these regions, various practical or perceived difficulties have prevented the methods from being adopted widely.

A slightly simplified version of these more economical methods was tested by Dr Mary Warrell (Centre for Clinical Vaccinology and Tropical Medicine, University of Oxford, United Kingdom) and colleagues, in which four injection sites are used on the first day of injection. To test it, they conducted the trial with a vaccine that is already in common use, and vaccinated healthy volunteers to compare antibody levels induced by the new method with those induced by each of the old two site and four site intradermal regimens, as well as the “gold standard” intramuscular regimen that is accepted internationally. They found that each of the more economical methods was just as effective as the intramuscular method at stimulating anti-rabies antibodies.

The authors claim that the simplified method has advantages over all three of the others, as it requires fewer clinic visits, is more practicable, more acceptable, and has a wider margin of safety even in inexperienced hands. Therefore, they say, it would be “suitable for use anywhere in the world where there are financial constraints, and especially where two or more patients are likely to be treated on the same day.” They conclude that the results provide sufficient evidence that their simplified four-site regimen meets all criteria necessary for clinical recommendation wherever the cost of the vaccine may be prohibitive.

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A Simplified 4-Site Economical Intradermal Post-Exposure Rabies Vaccine Regimen: A Randomised Controlled Comparison with Standard Methods.
Warrell MJ, Riddell A, Yu L-M, Phipps J, Diggle L, et al. (2008)
PLoS Negl Trop Dis 2(4): e224.
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Written by Anna Sophia McKenney