Post-exposure Prevention Measures

Post-exposure Prophylaxis (PEP) of Humans

Note: Specific PEP guidelines have changed since this writing. See the links in the Disclaimer for up-to-date recommendations.

In 2001, post-exposure prophylaxis (PEP) became a reportable condition in Washington State (WAC 246-101). Healthcare providers should immediately report any PEP treatment on the appropriate form to their local health department.

In Washington state, PEP is provided by physicians and some nurse practitioners and physician's assistants. Only a few local health departments offer PEP. Providers should know that all PEP products can be obtained within 24 hours directly from the product distributor. Any provider encountering difficulty obtaining PEP products should contact the Communicable Diseases Epidemiology Section at 206.361.2914 or toll-free at 1.877.539.4344.

There are three components to PEP:

1. local treatment of wounds;
2. provision of passive immunity with purified specific immunoglobulin; and
3. the induction of active immunity with rabies vaccine.

All three components are critical to the effective prevention of rabies.

Table 3: Post-exposure Prophylaxis Regimens

^* Persons who have been previously vaccinated should not receive HRIG.

Local treatment of wounds: Immediate and extensive washing of all bite wounds, scratches, or other sites of potential exposure for 10 minutes with soap and water is arguably the most important measure for preventing rabies following an exposure to a rabid animal. Experiments done in animals suggest that thorough and vigorous cleansing to the depth of the wound with a 20% soap solution can reduce the risk of developing rabies by up to 90%13. Tetanus booster vaccine (Td) should be given if indicated.

Immunoglobulin Administration: Purified human anti-rabies immunoglobulin (HRIG) provides rapid protection against rabies for one to two weeks after exposure—while the more lasting vaccine-induced immune response is developing. HRIG should be given to any previously unvaccinated person regardless of their age, type of exposure, or time since exposure. HRIG can be given through the seventh day following administration of the first dose of vaccine but should not be given after this time because it could interfere with the antibody response to the vaccine. HRIG is not given for pre-exposure prophylaxis. Nor should HRIG be given as part of PEP in a person who has previously been vaccinated with HDCV, RVA, or PCECV or who has a documented rabies antibody titer to any vaccine.

The recommended dose of HRIG is 20 IU/kg body weight (0.06 ml/lb body wt). As much of the dose as is anatomically feasible should be infiltrated in the area around the wound(s). The remaining volume is administered intramuscularly at a site distant from vaccine inoculation, such as the gluteal area. Providers should note that this is a new recommendation14; until recently, the ACIP recommended that only up to half of the HRIG be infiltrated in the area of the wound.

Adverse Effects of HRIG: HRIG has been associated with very few adverse reactions. Local pain and low-grade fever occur infrequently following HRIG injection. There is no evidence that HIV, hepatitis B, hepatitis C, or other blood-borne infections have ever been transmitted by HRIG in the United States. No fetal abnormalities have been associated with HRIG use during pregnancy.

Vaccine Administration: Primary post-exposure immunization with HDCV, RVA , and PCECV is given intramuscularly (IM) in a regimen of five 1-ml doses. The first dose is given as soon after exposure as possible (day 0). The remaining four doses are given on days 3, 7, 14 and 28 following the first dose.

For adults and older children, the vaccine should be injected into the deltoid muscle. For small children and infants, the muscles of the anterolateral thigh can be used. Vaccine should never be given in the gluteal area or in the same anatomical site as HRIG. If an individual misses any vaccine doses during the first two weeks of the regimen, providers should consult the vaccine manufacturer. The schedule should be adjusted to ensure that four doses of vaccine are received during the first 14 days. The fifth dose can be given on day 28. Persons who have already received pre-exposure prophylaxis still require two booster doses of vaccine on day 0 and day 3.

Details about the human vaccines currently licensed by the United States are available.

Efficacy of PEP: Rabies post-exposure prophylaxis is very effective. No cases of rabies have ever been reported in persons bitten in the United States by laboratory-confirmed rabid animals who were treated with local wound care, HRIG, and at least five doses of HDCV. However, outside the United States there have been at least 13 documented cases of rabies developing in people given modern tissue culture-derived vaccine10. The reasons for these failures are varied, but all involve some deviation from the PEP recommendations. In some instances, local wound care was not done. In others, rabies immunoglobulin was not given. In addition, several individuals in whom the vaccine was administered into the gluteal region (rather than the deltoid as is recommended) subsequently developed rabies. Each of these cases provides a tragic illustration of how important it is to follow the post-exposure recommendations exactly.

Table 4: Rabies Immunizing Products, 2002

Note: If not available locally, all immunizing products can be obtained within 24 hours directly from the distributor.

Historical note and disclaimer