Early Measles Vaccination in Infants Less than 12 Months: Global Practices, Immunity Outcomes, and Implications for Disease Prevention.

Measles continues to be a global threat that can lead to serious complications, especially in young infants. The World Health Organization recommends a two-dose vaccine series at different timeframes depending on local measles transmission rates; starting at 9 months in areas with ongoing transmission and 12 months in areas with low transmission. This leaves the majority of infants under 12 months of age at risk of infection. Early vaccination has been proposed, however, the interplay between early vaccination, presence of maternal antibodies, and immaturity of the infant immune system may lead to a less robust immune response as suggested by some studies. Other studies suggest that infants vaccinated early have a similar response to older infants, especially after receiving the full vaccination series. The implications of early vaccination are discussed in both outbreak and non-outbreak settings, though further studies are needed to guide optimal timing of early vaccination.