Doi:10.1093/aje/kwn253 Original Contribution Measles-Mumps-Rubella Vaccination and Asthma-like Disease in Early Childhood

The authors evaluated the association between receipt of measles-mumps-rubella (MMR) vaccine and asthma-like disease in early childhood in a Danish nationwide cohort study (N 871,234). Two outcomes were included: hospitalizations with asthma diagnoses and use of anti-asthma medications (for a subset of the cohort only). Poisson regression was used to estimate rate ratios according to vaccination status. MMR-vaccinated children were less often hospitalized with an asthma diagnosis (rate ratio (RR) 0.75, 95 % confidence interval (CI): 0.73, 0.78) and used fewer courses of anti-asthma medication (RR 0.92, 95 % CI: 0.91, 0.92) than unvaccinated children. This ‘‘protective’ ’ effect of MMR vaccine was more pronounced for hospitalizations with severe asthma diagnoses (status asthmaticus: RR 0.63, 95 % CI: 0.49, 0.82) and use of medication that was highly specific for asthma (long-acting b2-agonist inhalant: RR 0.68, 95 % CI: 0.63, 0.73). MMR vaccine was not negatively asso-ciated with anti-asthma medications often used for wheezing illnesses in early childhood (systemic b2-agonist: RR 1.02, 95 % CI: 1.01, 1.02). These results are compatible not with an increased risk of asthma following MMR vaccination but rather with the hypothesis that MMR vaccination is associated with a reduced risk of asthma-like disease in young children. asthma; measles-mumps-rubella vaccine; vaccination; vaccine