Duke Medicine: New approach to flu vaccines may help nursing babies

Babies under a year of age are at nearly as high a risk for flu problems as the elderly, yet there is not an approved flu vaccine for children under 6 months old.

In a study sponsored by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health, doctors at Duke University Medical Center are investigating a new approach to newborn protection during flu season. They are testing two forms of vaccines taken by nursing mothers: The traditional shot in the arm versus the newer nasal vaccine. The mothers form protective substances called antibodies that may be passed in their breast milk to their babies, and the researchers are testing to see which vaccine produces more protective antibodies in the breast milk.

"Our idea is that the nasal vaccine may be better for babies because of the type of antibodies that the mother forms when the vaccine mist is sprayed into the nose as opposed to having the vaccine delivered through a shot," said investigator Dr. Emmanuel "Chip" Walter, a professor of pediatrics, who is overseeing the clinical trial at Duke.

The nasal vaccine results in mucosal antibodies that may be passed through breast milk better than other types of antibodies. Right now the only way to protect children under 6 months is either for mothers to get a flu shot when they are pregnant or a cocooning approach - have all family members get protection through a flu vaccine.

Many women miss the opportunity to get a flu shot when they are pregnant and some deliver their newborns just before the flu vaccine becomes available. Through this study the researchers may learn which vaccine protects babies more, for those mothers receiving a flu vaccine after the birth of their baby.

The Duke team, which is part of the larger, multi-center study, is still enrolling mothers who have a 1- to 4-month-old baby and who are nursing their child. The study is also being conducted at other Vaccine and Treatment Evaluation Units (VTEUs) funded by the national allergy institute.

"As we learn more about the two vaccines and how antibodies are passed to nursing babies, we may find that this is a good opportunity for children, especially those who were born between May and September, because the mothers have very little immunity from the previous year's flu shot in their system at that time," Walter said. "When you look at flu strains year to year, the rate of infection in newborns is nearly as high as in the elderly, so this is a very vulnerable population."

For more information on the flu study, call Lynn Harrington at 919-620-5353.