CDC Expert Commentary

Changes to Rabies Vaccine Recommendations

Brett W. Petersen, MD, MPH

Disclosures

February 22, 2011

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Hello, I'm Dr. Brett Petersen from CDC's rabies program. I am here today to speak with you as part of the CDC Expert Commentary Series on Medscape.

Rabies is a deadly viral disease that is fatal once the clinical symptoms are manifest. However, rabies can be prevented if postexposure prophylaxis (PEP) is administered following an exposure to the rabies virus. Today, I'd like to talk with you about some changes to the recommendations for rabies PEP.

Despite the success of animal vaccination and control programs in decreasing the number of human cases in the United States, human exposures to the rabies virus remain common. In the United States, approximately 39,000 people receive PEP each year due to exposures to the rabies virus. The success of rabies PEP is dependent on proper vaccine administration. With that in mind, it is important that clinicians and other healthcare workers learn about changes to the PEP administration regimen and begin to institute them accordingly.

Recently, the Advisory Committee on Immunization Practices (ACIP) updated its recommendation for PEP, reducing the regimen to 4 doses over 2 weeks, as opposed to 5 doses over 1 month.

For persons previously unvaccinated with rabies vaccine, the updated ACIP recommendations call for 4 1-mL doses of human diploid cell vaccine (HDCV) or purified chick embryo cell vaccine (PCECV) administered intramuscularly in the deltoid for adults or anterolateral thigh for infants and small children. The first dose should be given as soon as possible after exposure in conjunction with rabies immunoglobulin (RIG). Additional doses should then be administered on days 3, 7, and 14 after the first vaccination.

This replaces the previous regimen, which consisted of 5 doses of vaccine, the first given directly after the initial exposure and subsequently on days 3, 7, 14, and 28.

You might have noticed that some vaccine packaging materials do not reflect the updated ACIP recommendations and instead urge the use of the previous PEP regimen. While such materials often provide sound guidance and information, the new ACIP recommendations should take precedence over materials that might not yet have been updated to reflect the modified regimen.

This is especially true considering the many benefits of the updated recommendations. If 100% compliance was to occur, ACIP estimates that the new regimen would save more than $16 million in costs to the US healthcare system.

In addition, ACIP identified no adverse events that were correlated to a failure to receive the fifth vaccine dose. In fact, the omission of the vaccine dose on day 28 might have some positive health benefits since some adverse reactions might be independent clinical events with each vaccine administration.

Furthermore, evidence from rabies virus pathogenesis data, experimental animal work, clinical studies, and epidemiologic surveillance lend further support to the 4-dose regimen. These studies indicated that 4 vaccine doses, in combination with RIG, elicited adequate immune responses and that a fifth dose of vaccine did not contribute to more favorable outcomes.

Outside of the 4-dose recommendation for PEP, recommendations for other rabies vaccination regimens remain unchanged.

For persons who previously received a complete vaccination series (pre- or postexposure prophylaxis) with a cell-culture vaccine or who previously had a documented adequate rabies virus-neutralizing antibody titer following vaccination with noncell-culture vaccine, the recommendation for a 2-dose PEP vaccination series has not changed.

Similarly, the number of doses recommended for persons with altered immunocompetence has not changed; for such persons, PEP should continue to comprise a 5-dose vaccination regimen with 1 dose of RIG. Recommendations for pre-exposure prophylaxis also remain unchanged, with 3 doses of vaccine administered on days 0, 7, and 21 or 28.

For more information on the rabies ACIP recommendations, visit www.cdc.gov/rabies.

Thank you.

Web Resources

CDC Rabies

Brett Petersen, MD, MPH, is a Lieutenant Commander in the United States Public Health Service. He currently serves as an Epidemic Intelligence Service Officer in the rabies program of CDC. His work focuses on the epidemiology of rabies and its application to both domestic and international prevention and control efforts. Prior to joining the CDC, Dr. Petersen received his MD from the University of Michigan Medical School and his Masters of Public Health from the Johns Hopkins Bloomberg School of Public Health. He completed his residency at the University of California San Diego (UCSD) Medical Center and is board certified in internal medicine. He is also a graduate of UCSD with a bachelor's degree in microbiology.

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