Simplification of Rabies Postexposure Prophylaxis: A New 2-Visit Intradermal Vaccine Regimen

American Journal of Tropical Medicine and Hygiene
Volume 101, Issue 6, 2019
http://www.ajtmh.org/content/journals/14761645/101/6

 

Perspective Piece
Simplification of Rabies Postexposure Prophylaxis: A New 2-Visit Intradermal Vaccine Regimen
Mary J. Warrell
https://doi.org/10.4269/ajtmh.19-0252
THE CURRENT SITUATION
Rabies encephalitis following a rabid dog bite is always fatal in unvaccinated patients, yet correct preventive vaccination has proved 100% effective. Rabies vaccine is frequently unavailable or unaffordable in rural areas of Asia and Africa, where up to 90% of rabies deaths occur.1 Gavi, the Vaccine Alliance, recently approved support for human rabies vaccine for postexposure prophylaxis (PEP), beginning in 2021. The success of this endeavor will depend on whether the expensive vaccines can be provided economically. Using small doses of vaccine intradermally (ID) is highly immunogenic and economical.2
The WHO has recently recommended the new IPC (Institut Pasteur du Cambodge) postexposure vaccine regimen consisting of 0.1 mL ID injection at 2 sites on days 0, 3, and 7.3 This is the same as the method recommended for 20 years, the Thai Red Cross (TRC) 2-site ID regimen, but without the day 28 dose (Table 1). The WHO decision to accept this regimen was based on preliminary serological data from some of the patients in a clinical trial.4 (The study used vaccine containing 0.5 mL/vial.) The full data remain unavailable a year later.2 Rabies vaccines do not contain preservatives and their use ID is off-label but is sanctioned by the WHO, provided that an opened vial is used within 8 hours. Attempts to use the TRC regimen in rural clinics where only a few dog bite patients are treated each month have failed, mainly because of vaccine wastage. This regimen has proved economical only in urban clinics seeing several patients a week. It seems unlikely that the new 1-week IPC method will solve that problem. Rabies immunoglobulin, officially recommended for all but the most trivial bites,3 is not expected to be available.