In the 0-30 day time period following vaccination, the incidence of febrile seizures with ProQuad (n=44; 1.4 per 1000 children) was similar to that observed in children receiving the measles, mumps, and rubella vaccine manufactured by Merck & Co., Inc., and the Varicella Vaccine live (Oka/ Merck) concomitantly (n=40; 1.3 per 1000 children).