RESUMEN
We evaluated the safety of a measles-mumps-rubella [MMR] immunization campaign for Saudi children [age range: 6-13 years] and gender differences in reporting post-MMR adverse events. After vaccinations were administered, we monitored 160 schools for 14 days and 19 hospitals in the 8 cities under study for 10 weeks. Incidence rates were: all MMR adverse events, 26.5/10,000 MMR vaccines [significantly higher in females than males]; Urabe strain aseptic meningitis, 1.0/295,000; fever, 40.2/10,000 [females] and 0.9/10,000 [males]; and parotitis, 5.4/10,000 [females] and 0.9/10,000 [males]. Combined MMR vaccine containing the Urabe mumps strain was safe for children aged 6-13 years. Gender differences regarding reactogenicity were evident and should be considered when designing future studies