Mother's flu shot protects newborns

Newborns can be protected from seasonal flu when their mothers are vaccinated during pregnancy, according to a study led by researchers at the Johns Hopkins Bloomberg School of Public Health.

The researchers observed a 63 percent reduction in proven influenza illness among infants born to vaccinated mothers while the number of serious respiratory illnesses to both mothers and infants dropped by 36 percent. The study is the first to demonstrate that the inactivated influenza vaccine provides protection to both mother and newborn. The findings were presented during the National Vaccine Advisory Committee meeting in Washington, D.C. on September 17 and will be published in the October 9 issue of the New England Journal of Medicine.

The inactivated influenza vaccine (the flu shot) is not licensed for infants younger than six months. The alternative nasal flu vaccine is not available for children under age 2. The flu shot has been recommended for pregnant women in the U.S. since 1997, although approximately 15 percent of pregnant women are vaccinated each year.

"Even though there is no flu vaccine for these children, our study shows that a newborn's risk of infection can be greatly reduced by vaccinating mom during pregnancy. It's a two for one benefit," said Mark Steinhoff, MD, the study's senior author and professor in the Bloomberg School's Department of International Health. "Infants under six months have the highest rates of hospitalization from influenza among children in the U.S. These admission rates are higher than those for the elderly and other high-risk adult groups."

The study was conducted in Bangladesh in collaboration with researchers from the International Centre for Diarrheal Disease Research (ICDDR,B). Researchers observed 340 mothers and their infants as part of the larger Mother's Gift vaccine evaluation study. The mothers were randomly selected to receive either flu vaccine or pneumococcal vaccine.

"Pregnant woman should be encouraged to be vaccinated for the flu to protect their infants and themselves," said Steinhoff.

Additional authors of the study include K. Zaman, S.E. Arifeen, M. Rahman, R. Raqui, N. Shahid and R.F. Breiman from the International Centre for Diarrheal Disease Research in Bangladesh. E. Wilson is with the Bloomberg School of Public Health and S. B. Omer is with Emory University.

The research was supported by the Bill & Melinda Gates Foundation, United States Agency for International Development (USAID), the NPVO Research Fund, Wyeth Pharmaceuticals Inc., the Thrasher Research Fund, Aventis Pasteur, ICDDR,B and the Johns Hopkins Bloomberg School of Public Health.