Early administration of measles, mumps, and rubella (MMR) vaccine at 5 to 7 months of age did not reduce the rate of hospitalizations for nontargeted infections before age 12 months in a Danish trial. “This well powered randomised controlled trial does not support the hypothesis of a non-specific effect of MMR vaccination on infection related hospitalisations in infants in a high income setting [with low exposure to MMR],” the authors conclude. “Early implementation of MMR vaccination should be based on the specific, protective effect against the vaccine targeted diseases.”
The randomized, double-blinded, placebo-controlled trial included 6,540 Danish infants aged 5 to 7 months. The infants received either standard-titer MMR vaccine or placebo (solvent only). The primary outcome measure was hospitalizations for infection from randomization to 12 months of age.
The results showed the following: “3,264 infants randomised to MMR vaccine experienced 786 hospitalisations for infection before age 12 months compared with 762 for the 3,272 infants randomised to placebo. In the intention-to-treat analysis the rate of hospitalisations for infection did not differ between the MMR vaccine and placebo groups (hazard ratio 1.03, 95% confidence interval 0.91 to 1.18). For infants randomised to MMR vaccine compared with those randomised to placebo, the hazard ratio of hospitalisations for infection with a duration of at least 12 hours was 1.25 (0.88 to 1.77), and for prescriptions of antibiotics was 1.04 (0.88 to 1.23). No significant effect modifications were found by sex, prematurity, age at randomisation, or season. The estimate did not change when censoring at the date infants received [diphtheria, tetanus, pertussis, polio, Hemophilus influenzae type B, and immunization with pneumococci conjugate vaccine] after randomisation (1.02, 0.90 to 1.16).”