Effectiveness of Measles Vaccination and Immune Globulin Post-Exposure Prophylaxis in an Outbreak Setting—New York City, 2013

Measles, mumps, and rubella vaccine (MMR) or immune globulin (IG) are routinely used for measles post-exposure prophylaxis (PEP). However, current literature on the effectiveness of measles PEP is limited and variable. Here, we examined the effectiveness of MMR and IG PEP among children exposed to measles during an outbreak in New York City (NYC) in 2013. Contacts were identified by the NYC Department of Health and Mental Hygiene between 13 March 2013 and 30 June 2013. Immunity to measles and receipt of PEP was determined for contacts. PEP effectiveness [(1 - relative risk of developing measles) × 100] was calculated for MMR, IG, and any PEP (MMR or IG) for nonimmune contacts aged