ST. LOUIS -- Saint Louis University will begin a human clinical trial this fall for a vaccine that seeks to prevent the Zika virus.

The university said Thursday funding from the National Institutes of Health will fund the trial. Lead researcher Dr. Sarah George said the goal is to make sure the vaccine is safe and measure the immune response to Zika.

The vaccine contains an inactivated version of the virus. After testing in St. Louis begins, the university plans a second study in Puerto Rico, which has been hit hard by the virus.

Zika is spread primarily through mosquito bites. More than 2,200 cases have been reported in the U.S. and its territories, including more than 400 pregnant women at risk of having babies with major deformities like microcephaly.