Shorter Pre-exposure Rabies Vaccination Schedule Effective

Shortening the rabies pre-exposure prophylaxis (PrEP) regimen is both effective and safe, a recent study published online in Clinical Infectious Diseases shows.

“In healthy adults, ID [intradermal] administration of a double dose of 0.1 ml of HDCV [human diploid cell culture rabies vaccine] over two-visits (day 0 and day 7) was safe and not inferior to the single-dose three-visit schedule,” writes Patrick Soentjens, MD, PhD, from the Institute of Tropical Medicine, Antwerp, Belgium, and colleagues.

According to the authors, rabies is a neglected global challenge, with a case fatality rate approaching 100%.

As a consequence, PrEP is a key component of rabies prevention and is recommended by the World Health Organization (WHO) for anyone at high risk of exposure to the virus because of their occupation, travel, or residence in a rabies-endemic area with poor access to timely and adequate PEP.

The standard PrEP schedule is comprised of 3 vaccinations given over a 28-day period. However, because this regimen is not always practical, effective, and safe, alternate schedules have been designed.

In their study, Dr Soentjens and colleague investigated the safety and efficacy of using an ID vaccine, with 2 doses administered 7 days apart.

The researchers recruited healthy participants (aged 18 to 47 years), from the Belgian Armed Forces, randomly assigning 500 of them to receive either two 0.1-mL doses of the ID HDCV rabies vaccine on days 0 and 7 (2ID), or a single 0.1-mL dose of ID HDCV on days 0, 7, and 28 (3ID).

One to 3 years later, the researchers gave participants in both groups a single booster dose of HDCV, in order to examine the anamnestic response.

A total of 211 participants in the 2ID group and 200 in the 3ID group completed the primary vaccination regimens and received a booster vaccination.

All participants in both groups had a rabies antibody titer >0.5 IU/mL on day 7 after the booster injection. “[S]ubjects exposed to the double-dose two-visit ID schedule had a geometric mean titer of 37 IU/ml, versus 25 IU/ml for the single-dose three-visit schedule (p<0.001),” the authors added.

The most common adverse event was a local reaction at the injection site, but this was typically mild and transient, according to the authors. After the primary vaccination, this type of reaction occurred more frequently in the 3ID group (51.8% vs 43.4%, P=.07). However, after the booster dose, it occurred more frequently in the 2ID group (38.8% vs 48.8%, P=.03).

“Data from the present study substantiates the safety and the immunogenicity of the 2ID regimen for rabies immunization in adult healthy travelers,” the authors conclude. “Shortened PrEP ID schedules, using simpler low-dose vaccine regimens, can be considered an illustration that less can be more,” they emphasize.

Dr. Parry graduated from the University of Liverpool, England in 1997 and is a board-certified veterinary pathologist. After 13 years working in academia, she founded Midwest Veterinary Pathology, LLC where she now works as a private consultant. She is passionate about veterinary education and serves on the Indiana Veterinary Medical Association’s Continuing Education Committee. She regularly writes continuing education articles for veterinary organizations and journals and has also served on the American College of Veterinary Pathologists’ Examination Committee and Education Committee.