The vaccine, to be marketed under the brand name Pediarix by SmithKline Beecham Pharmaceuticals, is a combination that protects against diphtheria, tetanus, pertussis, polio and the Hepatitis B virus.
FDA officials said it will be given in a series of three shots at ages 2, 4 and 6 months. Before Pediarix, protection against these diseases would have required nine shots.
Dr. Karen Midthun, director of the FDA's office of vaccine research and review, said that in clinical trials involving thousands of infants, Pediarix was found to be as effective at the nine-shot regimen.
She said there was a slight increase in fever and other side effects from the new vaccine when compared to the previous vaccination series. The side effects included pain, redness, swelling and "fussiness."
"The advantage of the new vaccine is convenience," said Midthun. "There also is sometimes a reluctance to administer so many injections at one time (under the nine-shot plan)."
She said it is expected the protection against the diseases will be found to be "comparable" to the protection from the separately administered vaccines.
Midthun said she did not know what the cost would be of the combined vaccine.