An experimental DNA vaccine to protect against disease caused by Zika infection has advanced to a larger study in humans, which will further evaluate the vaccine’s safety and immune response as well as optimal dosing, the National Institutes of Health announced today. Initial findings from an ongoing smaller trial in humans indicate the candidate vaccine is safe and able to induce a neutralizing antibody response, the agency said. The new two-part trial aims to enroll at least 2,490 healthy participants in areas of confirmed or potential active mosquito-transmitted Zika infection, including Houston, Miami, Puerto Rico, Brazil, Peru, Costa Rica, Panama and Mexico. Most of the participants will be followed for nearly two years.