Redefined Risk Categories
Recommendations for PrEP depend on the level of a person's risk for being exposed to rabies. The Work Group redefined risk categories into five groups, with level 1 involving activities with the highest risk and level 5 involving those with the lowest risk (Table). The highest risk categories (levels 1 and 2) include exposures that might be unrecognized (i.e., not perceived by the exposed person); for example, a small scratch to the skin during an inconspicuous personal protective equipment breach might not be noticed by persons testing neural tissue from a rabid animal or conducting ecologic studies on bats in the field. For persons with risk for unrecognized exposures, checking serial titers has historically been advised to ensure maintenance of persistently elevated rabies antibody titers; in its recent discussions, ACIP upheld this guidance because the assumption is that high titers might provide some protection when PEP is not sought for an unrecognized exposure. Recognized exposures, as defined by ACIP, are those bites, scratches, and splashes for which PEP would be sought because the exposures are usually registered by a person as unusual (e.g., contact with a bat) or painful (e.g., bite or scratch from a raccoon). The Work Group concluded that most high-risk activities involving live animals (e.g., providing veterinary health care or participating in outdoor activities in countries with endemic CRVV) are associated with only recognized exposures (risk categories 3 and 4); ACIP concluded that checking serial titers for these persons is unnecessary because recognized exposures should always prompt evaluation for PEP. Rabies vaccination recommendations for each of the redefined risk categories is summarized under Recommendations.
Risk categories might change over a person's lifetime. Some persons for whom PrEP is indicated might have elevated risk for a limited period (e.g., during a summer internship working with wildlife or a month-long vacation to a rural village where CRVV is enzootic [risk category 4]). After the event has passed, risk level and associated recommendations for such persons will change. Shifts in risk categories are explained in the management of deviations from the recommendations section under Clinical Guidance.
Morbidity and Mortality Weekly Report. 2022;71(18):619-627. © 2022 Centers for Disease Control and Prevention (CDC)