Test-tube experiments showed antibodies culled from recipients of the new vaccine were powerful enough to kill strep.
Then Kasper injected pregnant mice with the women's antibodies, which protected three-fourths of the baby mice from the infection.
It will take several years to develop a shot, especially since Kasper's vaccine fights just one of the five subtypes of Group B strep that exist.
North American Vaccine Inc. has licensed rights to Kasper's vaccine and is presently planning the research necessary to win Food and Drug Administration approval.
The company is working with the NIH to determine whether the vaccine would harm the fetus. The vaccine may possibly be used on teen-age girls, to give them antibody protection before they become pregnant.
The vaccine "is not infectious," Kasper said. "We don't see that there's any defined risk in immunizing pregnant women," particularly because the riskiest fetal development is completed by the third trimester.
The vaccine may also help growing numbers of adults with immune systems weakened by AIDS or cancer who are suffering from serious strep infections.
This story was compiled using Assoicated Press dispatches.