Post exposure studies with human diploid cell rabies vaccine and purified chick embryo cell vaccine: comparative serological responses in man

Post-exposure prophylaxis (PEP) for rabies with purified chick embryo cell vaccine: a systematic literature review and meta-analysis

INTRODUCTION

Fifteen million people each year receive post-exposure prophylaxis (PEP) to prevent rabies, yet the disease remains neglected and highly under-reported.

AREAS COVERED

In this systematic literature review, we assessed the immunogenicity, efficacy, and safety of a purified chick embryo cell-culture rabies vaccine (PCECV) for PEP against rabies by intramuscular (IM) or intradermal (ID) administration. We performed meta-analyses to compare immunogenicity according to the route of vaccine administration, study population, and PEP regimen, such as number of doses, and concomitant rabies immunoglobulin.

EXPERT COMMENTARY

There were 54 estimates of immune responses to vaccination, which showed that in the overall population, after starting PEP with PCECV by the IM or ID route (≥2.5 IU per dose), almost all individuals had rabies virus neutralizing antibody (RVNA) titers above the World Health Organization (WHO) recommended serological threshold for an adequate immune response to vaccination (RVNA ≥0.5 IU/ml by day 14). In the overall population, PCECV had an acceptable safety profile. However, given that there are 59,000 human rabies deaths reported annually, the challenge is to improve access to PCECV for PEP against human rabies.

Failures of post-exposure rabies prophylaxis

Rabies remains a public health problem in many emerging countries. Virtually all is known that should enable us to eliminate this scourge by controlling the disease in canine populations and by diligent provision of WHO recommended post-exposure prophylaxis (PEP). Nevertheless, post-exposure prophylaxis failures do occur. Most common failures are due to deviations from WHO management recommendations and lack of essential biologicals. True failures, where all was done according to WHO recommendations, are fortunately extremely rare. Presented are seven such deaths. Other examples of common management deviations that resulted in deaths are also shown.

A global review of rabies vaccines for human use

Rabies is one of the oldest known diseases of mankind, yet it has been only slightly more than 100 years since Pasteur developed the first vaccine for post-exposure treatment. Since this first crude nerve tissue vaccine, numerous other rabies vaccines for human use have been developed and used with varying degrees of effectiveness and safety. When used appropriately, new cell culture vaccines provide nearly 100% protection with a high degree of safety: yet over 40,000 people world-wide die from rabies each year. Several pre- and post-exposure controlled vaccine trials and clinical studies have shown that the purified chick embryo cell (PCEC) vaccine, Rabipur, is as safe and effective as the rabies human diploid cell vaccine (HDCV), which is currently considered the gold standard. Additionally, PCEC vaccine does not result in immune-mediated hypersensitivity reactions following booster doses seen in about 6% of those receiving HDCV boosters following an initial series of HDCV.

Safety and immunogenicity of Lyssavac Berna human diploid cell rabies vaccine in healthy adults

A clinical trial testing the safety and immunogenicity of a newly developed human diploid cell rabies vaccine (Lyssavac-HDC) was conducted on subjects at three colleges of veterinary medicine in the United States. Lyssavac-HDC is a sterile lyophilized vaccine containing no antibiotics or preservatives and is administered intramuscularly as a 0.5 ml dose of vaccine containing at least 2.5 i.u. of rabies inactivated antigen per dose. Subjects were given either a three dose pre-exposure series (days 0, 7, and 28), followed by one booster dose of vaccine (day 360); or a five dose simulated post-exposure series of injections (days 0, 3, 7, 14, and 28). All subjects in the post-exposure and pre-exposure groups possessed adequate levels of rabies neutralizing antibody (> or = 5) when tested on day 14 and day 28, respectively. Subjects in the pre-exposure group demonstrated a vigorous anamnestic response after the administration of one booster dose of vaccine on day 360. The type and severity of local and systemic reactions observed were comparable to other primary cell culture rabies vaccines. Significantly, there were no type III hypersensitivity reactions reported in subjects previously immunized with Lyssavac-HDC after the administration of a booster dose of vaccine on day 360.