Rabies Post-Exposure Prophylaxis (PEP) and Pre-Exposure Prophylaxis (PrEP)

Rabies Virus Overview

Rabies is a neurotropic virus, primarily transmitted through the saliva of infected mammals. It causes acute encephalitis, leading to progressive neurological symptoms and death if untreated. Prevention through vaccination is critical for individuals at risk of exposure.

Immunoglobulin Administration

Rabies immunoglobulin (RIG) provides immediate, passive immunity by directly neutralizing the rabies virus at the wound site. Human rabies immunoglobulin (HRIG) is typically preferred. The entire calculated dose should be infiltrated into and around the wound(s), if anatomically feasible; any remaining volume should be injected intramuscularly at a site distant from vaccine administration.

Rabies Vaccine Regimens

Modern rabies vaccines are cell-culture based and are highly effective. Different vaccine schedules exist for PEP and PrEP. These vaccines stimulate the body to produce its own antibodies against the rabies virus, providing active immunity.

Post-Exposure Prophylaxis (PEP)

PEP is initiated following a potential exposure to the rabies virus. It typically involves a combination of HRIG and a series of vaccine doses. The standard PEP schedule includes four doses of the vaccine administered over a 14-day period. The schedule might be adjusted based on prior vaccination status.

Pre-Exposure Prophylaxis (PrEP)

PrEP is recommended for individuals at high risk of rabies exposure, such as veterinarians, animal handlers, and travelers to regions where rabies is endemic. PrEP typically involves two or three doses of the vaccine, depending on the specific vaccine used. Periodic booster doses might be recommended for individuals with ongoing risk of exposure. Serologic testing is used to confirm adequate antibody titers in individuals who have received PrEP. Antibody titers should be maintained above an established threshold to demonstrate adequate protection. Booster doses are administered as needed to maintain those titers.

Monitoring and Booster Doses

For individuals receiving PrEP, periodic serologic testing (measuring rabies virus neutralizing antibody [RVNA] titers) is recommended to assess the level of protective immunity. If the titer falls below the accepted level, a booster dose of the vaccine is administered. The frequency of serologic testing and the need for booster doses are determined by ongoing risk of exposure and individual factors. People at continued risk should have their antibody titers checked every two years and receive booster doses if needed.

Factors Influencing Immune Response

The effectiveness of rabies vaccines can be influenced by several factors, including the individual's immune status, underlying health conditions, and certain medications. Immunocompromised individuals may require more frequent monitoring of antibody titers and may not develop adequate protection from standard vaccination schedules.