CDC Recommends Use of a Reduced Vaccine Schedule for Postexposure Rabies Prophylaxis

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The Centers for Disease Control and Prevention (CDC) recommends reducing the postexposure prophylaxis (PEP) to prevent human rabies from a 5-dose regimen to a 4-dose regimen.

The recommendation come from the Advisory Committee on Immunization Practices (ACIP) and is based in part on evidence from rabies virus pathogenesis data, experimental animal work, clinical studies, and epidemiologic surveillance.

Previously, ACIP recommended a 5-dose rabies vaccination regimen with human diploid cell vaccine (HDCV) or purified chick embryo cell vaccine (PCECV). The new recommendations call for a reducing the number of vaccine doses to four as the studies indicate that 4 vaccine doses in combination with rabies immune globulin (RIG) elicited adequate immune responses. The fifth dose of vaccine was not found to contribute to more favorable outcomes.

Rabies is a preventable viral disease of mammals most often transmitted through the bite of a rabid animal. Rabies is caused by RNA viruses in the family Rhabdoviridae, genus Lyssavirus. The virus is transmitted in the saliva of rabid mammals via a bite. The incubation period for rabies usually ranges from 1 to 3 months after exposure, but can range from days to years.

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When the rabies virus infects the central nervous system, it causes encephalopathy and ultimately death. Early symptoms of rabies in humans are nonspecific, consisting of fever, headache, and general malaise. As the disease progresses, neurological symptoms appear and may include insomnia, anxiety, confusion, slight or partial paralysis, excitation, hallucinations, agitation, hypersalivation, difficulty swallowing, and hydrophobia (fear of water). Death usually occurs within days of the onset of symptoms.

Over the last 100 years, rabies in the United States has changed dramatically. More than 90% of all animal cases reported annually to CDC now occur in wildlife. The principal rabies hosts today are wild carnivores and bats rather than domestic animals. The number of rabies-related human deaths in the United States has declined from more than 100 annually at the turn of the century to one or two per year in the1990's.

Modern day prophylaxis has proven nearly 100% successful. In the United States, human fatalities associated with rabies occur in people who fail to seek medical assistance, usually because they were unaware of their exposure.

Medical care consists of prompt wound care and the administration of rabies immune globulin (RIG) and PEP vaccine. For persons previously unvaccinated with rabies vaccine, the reduced regimen of 4 1-mL doses of HDCV or PCECV should be administered intramuscularly. The first dose of the 4-dose course should be administered as soon as possible after exposure (day 0). Additional doses then should be administered on days 3, 7, and 14 after the first vaccination. ACIP recommendations for the use of RIG remain unchanged.

The full report can be read here.

Source
Centers for Disease Control and Prevention

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