Preemies respond to immunizations

Babies born prematurely generate a protective immune response to two routine vaccines as strongly as full-term babies do. The finding casts doubt on a commonly held view that premature babies given the chickenpox and measles-mumps-rubella (MMR) vaccines at the same age as full-term infants don’t get the same benefit. Because of that perception, some pediatricians have delayed giving preterm infants the shots, going against medical authorities’ recommendations.

Neonatologist Carl D’Angio of the University of Rochester in New York and his colleagues gave initial doses of the chickenpox and MMR vaccines to 32 babies at age 15 months, a typical age for starting these shots. Half of the children had been born at full-term and half at roughly 6.5 months of pregnancy.

Blood drawn 3 to 6 weeks after the shots showed that just as many preterm as full-term infants had protective concentrations of antibodies against the diseases, the researchers report in the March Pediatrics.

Earlier research had shown that the polio vaccine and the combined diphtheria-pertussis-tetanus vaccine—both routinely given in three doses between 2 and 6 months, with boosters later—work equally well in preterm and full-term infants.

Some vaccines, however, don’t fit that pattern, D’Angio cautions. The vaccine against the Haemophilus influenzae type b (Hib) meningitis microbe sometimes doesn’t generate as robust a response in preterm babies.

The reason for the lack of response isn’t clear, says D’Angio. Similarly, the hepatitis B vaccine, when given at birth, isn’t as effective in preemies as in full-term infants.