Delayed dermal hypersensitivity following killed measles vaccine. Experience in 9-month-old infants.

Skin tests with measles and poliomyelitis vaccines were performed on both 9-month-oldinfants who were immunized previously with killed measles vaccine grown in chick embryos and 9-month-old control infants who were unimmunized. Positive tests to both vaccines occurred only in those infants previously immunized with killed measles vaccine. Reactions to intradermal poliomyelitis vaccine were not related to prior parenteral poliomyelitis immunizations, but seemed dependent on sensitization with some component of killed measles vaccine. It is not known whether this dermal hypersensitivity is in any way related to the bizarre systemic reactions following the administration of live measles vaccine or exposure to natural measles in children previously immunized with killed measles vaccine.