Objective: To examine the response to measles-mumps-rubella (MMR) vaccine among children with and without mild illness.
Design: Prospective cohort.
Participants: A total of 386 children aged 15 to 23 months.
Main outcome measures: Seroconversion rates to measles, mumps, and rubella in ill and well children.
Setting: Six public health immunization clinics in two counties in the greater metropolitan Atlanta, Ga, area from February 1992 to April 1993.
Results: Acute upper respiratory tract infection, otitis media, and diarrhea were observed in 128 (33%), 41 (11%), and 13 (3%) of the children (groups are not mutually exclusive); 157 children had one of these mild illnesses and 229 were well. Overall seroconversion rates were 98% for measles, 83% for mumps, and 98% for rubella antigens. Measles seroconversion rates for ill children compared with well children, respectively, were as follows: upper respiratory tract infection, 99% vs 97%; mild fever, 98% vs 97%; otitis media, 98% vs 98%; diarrhea, 100% vs 98%; and any mild illness, 99% vs 97%. Estimates of the magnitude of antibody response to measles, mumps, and rubella antigens were the same for children with and without mild illness. There was no association of mild illness with increased rates and severity of adverse events reported in the 2 weeks after vaccination.
Conclusions: Vaccinating children who present with mild illnesses with MMR vaccine is a safe and efficacious practice. These results support recommendations of the Advisory Committee on Immunization Practices and the American Academy of Pediatrics.