Experimental group B strep vaccine shows promise

An experimental vaccine cut the chances of a pregnant woman carrying group B strep bacteria, a leading cause of blood and brain infections in newborns, U.S. researchers said on Friday.

They said pregnant women who got the Group B Streptococcus vaccine were about one third less likely to carry the bacteria in the vagina and 43 percent less likely to carry the organism in the gut.

“It’s very exciting,” said Sharon Hillier of the University of Pittsburgh School of Medicine, who led the study. “We’ve shown development and testing of such a vaccine is possible.”

Hillier presented the study at a meeting of the Infectious Diseases Society of America in Philadelphia.

Group B Streptococcus live in the vagina and lower intestine of 15 percent to 40 percent of all healthy women in the United States. It is different from group A strep, the kind that causes “strep throat.”

Because group B strep poses a threat to newborns during labor and delivery, pregnant women are routinely tested and infected women are given intravenous antibiotics during labor to protect the baby.

But this strategy is imperfect, Hillier said in a telephone interview.

Not all infections can be prevented with antibiotics, and women must get to the hospital early enough during labor to receive the antibiotics, she said.

Group B strep infections cause disease in one in every 2,000 babies in the United States. It can also cause severe illness in pregnant women, the elderly and adults with chronic illnesses.

The researchers studied 650 sexually active women aged 18 to 40 who did not have the bacteria in their vagina or rectum at the start of the trial. None was pregnant.

Half of the women were in the study got a dummy vaccine and the other half got the group B strep vaccine.

After 18 months, they found women who received the vaccine were about a third less likely to carry the bacteria in the vagina and about 43 percent likely to carry the organism in the gut.

Hillier said the benefit is modest, but it is enough to prove to the government and industry that it would be possible to make a vaccine that might be even more effective at controlling group B strep infections.

The research was funded by the National Institute of Allergy and Infectious Diseases, a part of the National Institutes of Health.

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By Julie Steenhuysen

CHICAGO (Reuters)