Measles risk for babies of MMR-vaccinated moms

Babies born to women who received the measles-mumps-rubella (MMR) vaccine lose their initial immunity-acquired vertically-to measles about 2 months sooner than babies born to women who have been naturally infected with the virus, according to a new study.

Researchers investigated the issue in the Netherlands, where some Dutch parents refuse MMR vaccination because of religious beliefs. In a large, cross-sectional study, the researchers, from the National Institute of Public Health and the Environment, compared antibody levels of infants in the general population with those of infants in orthodox Protestant communities, where few children are vaccinated and outbreaks of measles, mumps, and rubella still occur.

They found that the duration of protection from measles was almost 2 months shorter in the infants in the general public than in the infants in the orthodox Protestant communities. They also found a lower concentration of antibodies to rubella in the infants born to the vaccinated versus unvaccinated mothers. No statistically significant difference existed in immunity to mumps between the two populations.

Generally speaking, all protection acquired vertically from vaccinated mothers was short-lived: 3.3 months for measles, 2.7 months for mumps, 3.9 months for rubella, and 3.4 months for varicella. The findings call into question whether MMR vaccination of children should begin sooner, particularly in areas where risk of exposure to measles is high.

Rubella and mumps do not typically occur in infants and generally are not as severe as measles, which is the leading cause of vaccine-preventable childhood death in the world. Annually, measles still causes about 160,000 deaths globally, according to the World Health Organization.

The researchers note that the proportion of European women of childbearing age receiving MMR vaccinations is increasing, which likely will further decrease the duration of protection of infants by maternal antibodies against measles and rubella and make a shorter duration of protection from mumps more pronounced.