Duration of Immunity: An Anamnestic Response 14 Years After Rabies Vaccination With Purified Chick Embryo Cell Rabies Vaccine

Recent cases of human rabies imported to Europe by travelers visiting India and Morocco demonstrate the relevance and value of receiving proper education regarding rabies prevention, including both preexposure vaccination and postexposure prophylaxis, prior to leaving for canine rabies–endemic countries.1,2 This is especially relevant for travelers planning on visiting countries in Asia and Africa where the majority of human rabies cases occur.3 Modern cell culture vaccines recommended by the World Health Organization (WHO), including purified chick embryo cell vaccine (PCECV), purified Vero cell rabies vaccine, and human diploid cell rabies vaccine (HDCV), provide a safe means by which travelers can be protected in the event of exposure to rabies virus. These vaccines have been licensed for several decades, but there are limited published data regarding the length of time after a person has received his or her primary rabies vaccination, for which they will continue to develop an anamnestic response after a booster dose of rabies vaccine has been administered.4,5 The vaccination recommendations for a person who has been vaccinated previously with a cell culture rabies vaccine and is subsequently exposed to a rabid animal include the administration of two booster doses of vaccine (one dose on day 0 and the other on day 3) without the administration of rabies immunoglobulin (RIG). However, the limited amount of available data has led to some confusion regarding booster recommendations in previously vaccinated persons who are subsequently exposed to rabid animals.6,7