Progress in Quest for Group B Strep Vaccine

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Study Shows Vaccine Is Effective in Women of Childbearing Age

By Charlene Laino
WebMD Health News

Reviewed By Louise Chang, MD

Oct. 30, 2009 (Philadelphia) -- Researchers are a step closer to developing a vaccine to protect pregnant women against a serious bacterial infection that is a leading cause of death and disability in newborns.

The bug is called group B streptococcus, more commonly referred to as group B strep. Pregnant women with group B strep infection or who are colonized with the bacteria -- meaning they carry the bug but aren't sick from it -- can transmit the bacteria to the fetus during delivery. It's commonly found in the vagina and rectum, with about 25% of women carrying it at any time; most will carry the bacteria and have no symptoms.

Group B strep can cause life-threatening infections in newborns in the hours after birth, during the first week of life, or even several months later, says Neil Fishman, MD, an infectious diseases specialist at the University of Pennsylvania.

Currently, women are screened a few weeks prior to delivery; if the test is positive, they are given antibiotics to wipe out the infection. "But this isn't perfect as the bacteria can be resistant to the antibiotics," Fishman tells WebMD.

Developing a vaccine against group B strep is a major goal, he says.

The new study involved 650 women of childbearing age who were not carriers of group B strep. About half were given the new vaccine. The women were checked for group B strep bacteria twice a month for 18 months.

The vaccine caused a modest but lasting reduction in group B strep colonization in the vagina and rectum, says researcher Sharon Hillier, PhD, of the Magee-Womens Research Institute at the University of Pittsburgh. Colonization of the genital or gastrointestinal tract is the major risk factor for infections.

The vaccine also elicited a strong immune response against the bacteria, she tells WebMD. And the vaccine was safe.

Emory University's Larry Pickering, MD, a senior advisor to the CDC's National Immunization Program, says that while preliminary, the work is very encouraging.

"It's important in that they showed it prevented colonization" in both the GI tract and vagina, he tells WebMD. "But there's still a lot of work to do."

SOURCES: Infectious Diseases Society of America 47th Annual Meeting, Philadelphia, Oct. 29-Nov. 1, 2009.

Neil Fishman, MD, University of Pennsylvania.

Sharon Hillier, PhD, Magee-Womens Research Institute, University of Pittsburgh.

Larry Pickering, MD, senior advisor, CDC's National Immunization Program; Emory University, Atlanta.

CDC web site: "Group B Strep Prevention."

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