According to the World Health Organization (WHO), an incorrect diluent for the measles/rubella vaccine most likely caused the recent deaths of 15 Syrian children in rural Idleb. Measles vaccine has to be reconstituted with a diluent prior to use, WHO said, and all evidence available to its assessment team indicated that vaccinators had mistakenly used Atracurim--a muscle relaxant used mainly as part of the anesthetic procedure for surgery--as that diluent. There's no evidence that the vaccine itself or its correct diluent caused the fatalities. Statement