Although it may be several months until pediatricians begin to use it, a new children’s vaccine recently approved by the U.S. Food and Drug Administration (FDA) is poised to nix the number of injections that babies get in their first year — from 15 to 9. Such a rigorous immunization schedule, experts say, has led some parents to resist immunizing their children. The introduction of the combination vaccine PEDIATRIX — to be given to infants at 2, 4, and 6 months of age for the prevention of diphtheria, tetanus, pertussis, hepatitis B, and polio — is the first five-in-one vaccine approved for use in the U.S. The vaccine, manufactured by GlaxoSmithKline, was approved after nearly a decade of studies, involving thousands of babies, proved it to be as effective as the separate shots. With the number of combination vaccines currently in development both here and abroad, in theory the immunization schedule could eventually be trimmed to three injections, lessening infants’ pain and discomfort. Experts say the implementation of combination vaccines also makes it easier for parents to comply with immunization schedules, limiting the number of trips to the pediatrician’s office. While PEDIATRIX had previously been approved for use in other countries, it marks a new milestone for the U.S. immunization program. Doctors will likely not make the switch to the biggest-ever combination vaccine until the American Academy of Pediatrics officially recommends it, a process that could take several months.