Vaccines for measles-mumps-rubella and varicella, or chicken pox, are effective in extremely preterm infants, even though preemies' immune systems are not as developed as full-term babies. This confirms a long-held assumption by pediatricians and neonatologists across the country.
"The assumption has always been that it would be OK, that very early babies would have enough immunity, but no one had formally researched the subject," said Carl D'Angio, M.D., associate professor of Pediatrics at the University of Rochester Medical Center, and author of a paper on the subject in Pediatrics this month. "I'm happy be able to reassure my colleagues and parents that it is OK."
The study, which included 16 term and 16 extremely preterm (born before about 6 months of pregnancy) infants born between May 2002 and May 2005, is the first of its kind to examine the antibody levels of measles, mumps, rubella and varicella in this population before and after vaccination. It was published in this month's Pediatrics.
The same number of preterm infants and full-term infants in the study reached a level of immunity considered protective against the diseases. This positive outcome, however, was not guaranteed because preemies' immune systems do not always react the same way as full-term infants. For instance, a change in the types of vaccine used in the UK apparently resulted in an increase in Haemophilus influenzae type b infections, like bloodstream infection or meningitis, in children. Children born prematurely appeared to be particularly at risk for this, alluding to potential problems this population may have with responding to vaccines.
That isn't the case for the MMR and chicken pox vaccines. "Now we can all breathe a sigh of relief. We were right," D'Angio said.