If you contract Zika during pregnancy, there’s currently no way to prevent your body from passing the virus along to your baby and triggering potentially devastating birth defects including microcephaly, a condition marked by abnormal head development, and other severe brain defects, according to the Centers for Disease Control (CDC).
It’s why researchers from Washington University School of Medicine are stoked about two new vaccines they’ve been testing to protect women from infecting their future babies before getting pregnant: In their study, which was recently published in the journal, Cell, the researchers injected female mice with a placebo or one of two experimental vaccines: The first (known as a “subunit vaccine,” in case you hear the term thrown around) is based on a genetic blueprint of the virus, while the other involves a live but weakened form of the Zika virus.
After vaccination, the mice became pregnant and were infected with Zika six days into their average 19-day pregnancies to simulate early-pregnancy exposure, when Zika can cause the most damage to a developing fetus. (The virus was passed along through the bloodstream, mimicking a bug bite. It didn’t simulate infection via semen, a totally different way to contract Zika during pregnancy, according to the CDC. This mode of transmission was not addressed in this experiment.)
A week after infection, researchers assessed the mothers, fetuses, and placentas of vaccinated mice, only to find that both vaccinations delivered: More than half of the placentas and fetuses given the subunit vaccine had no detectable trace of Zika, while the live-but-weakened vaccine left 78 percent of placentas and 83 percent of fetuses completely Zika-free.
In a second experiment, researchers assessed pregnancy outcomes under similar circumstances. The vaccinated mothers didn’t just remain healthy: Their babies were born with no detectable complications or trace of Zika.
Both vaccines appeared to have shifted the animals’ immune systems into high gear: Unlike mice given the placebos, vaccinated mice produced high levels of the antibodies that neutralize Zika, according to study authors.
While human studies are needed to confirm these findings and assess any adverse side effects, Zika-fearing women who’d like to have kids one day can rejoice that help is on the way.