Cases of Zika virus infection in Florida are continuing to rise, and the Centers for Disease Control and Prevention have issued travel advice urging pregnant women not to travel to certain parts of the country. The good news is that scientists testing three new types of Zika vaccine have found that they all work safely and rapidly in monkeys. One of the vaccines is made from killed virus grown in culture, another is based on a small piece of DNA containing the genetic information coding for the outer coat of Zika, and the third is made by adding part of that same outer coat to a common cold adeno virus. Trials on humans are the next step, as Chris Smith finds out from Dan Barouch who is leading the effort at Harvard Medical School