An experimental vaccine from Sanofi-Aventis proved effective in preventing infection with cytomegalovirus, a virus that can harm babies if it infects mothers during pregnancy, researchers report in the March 19 New England Journal of Medicine.

 

“In many ways, this was a surprising result. Many people in the field felt it would be very difficult to prevent infection in mothers. We thought the best we could hope for was a vaccine for women that would prevent infection in a baby,” said lead author Robert Pass, MD, of the pediatrics department at the University of Alabama at Birmingham.

 

The vaccine involved 464 women 14-40 in Alabama. When the study started none of the participants were pregnant and none had a history of CMV.

 

CMV does no serious harm to most people but can cause permanent deafness and mental retardation in babies born to mothers who were infected during pregnancy. Annually, roughly 30,000 to 40,000 U.S. children are born with congenital CMV infection, with about 8,000 cases resulting in permanent disabilities. The virus can be transmitted through saliva and other bodily fluids.

 

The women were given three shots of the experimental CMV vaccine or a placebo. During the next three years, 8% of the women who had gotten the CMV vaccine developed CMV infection, compared to 14% of women who had gotten the placebo shots.

 

“Vaccine efficacy was 50%,” Dr. Pass said.

 

Sanofi-Avensis will need to succeed in a larger randomized trial to gain regulatory approval.