[Efficacy of intradermal regimen using Japanese rabies vaccine for pre-exposure prophylaxis]

In Japan, only one vaccine is commercially available for rabies (Chemo-Sero-Therapeutic Institute (Kaketsuken), Kumamoto, Japan). It is a tissue-cultured inactivated vaccine made using purified chick embryo cells (PCEC-K) and administered subcutaneously using a schedule differing from that recommended by the World Health Organization (WHO). The current regimen of pre-exposure prophylaxis for rabies in Japan consists of three subcutaneous administrations of PCEC-K vaccine at 0, 28, and 180 days, requiring 6 months to complete. With the exception of a few imported cases, Japan is rabies-free and rabies vaccine production is small. Globalization should trigger rabies re-emergence in Japan, however, we would have to determine whether PCEC-K vaccine is effective through intradermal administration following the WHO-recommended regimen. In a study of 50 healthy volunteers without a history of rabies vaccination and all of whom provided, PCEC-K vaccine (0.1 mL, 2 sites) was administered intradermal by on days 0, 7, and 28, and the viral neutralizing antibody level (VNA) against rabies virus was tested using the rapid fluorescent focus-inhibiting test (RFFIT) on days 0, 14, 28, 42, 56, 84, and 208. On day 42, all individuals showed adequate VNA (GMT: 3.21 IU /mL), maintained for 84 days. VNA acquisition differed slightly with the PCEC-K vaccine lot and local adverse effects were minor. The intradermal PCEC-K regimen was found to be safe and effective in inducing adequate VNA using a smaller amount of vaccine within a shorter period.