Vaccines protect unborn mice from Zika infection

The researchers did not assess whether the vaccines are safe and effective for use during pregnancy.

Such studies couldn’t really be done in mice, Dr Diamond explained, because mouse pregnancies only last 19 days. That doesn’t allow enough time for a protective immune response to develop before the pups are born.

Additionally, this study did not address the question of whether the vaccines work when pregnant women are infected with Zika through sexual contact. It is possible that Zika virus in semen can travel to the uterus and then to the fetus without passing through the bloodstream.

“The question is, ‘Would the immunity still hold up if the virus does not pass through the bloodstream?’“ Dr Diamond said. “We think it will hold up, but that has to be tested.”