dr. gary nabel has a lot of experience when it comes to vaccine development. >> from my past experience in vaccines, what i learned was that you really need to be way ahead of the curve. >> reporter: he's chief scientific officer of french pharmaceutical giant sanafee. he spent more than a decade leading the national institutes of health vaccine research center. >> it causes you to pull the trigger and really launch a vaccine program when is you see that there are serious public health effects. >> reporter: the zika virus qualifies. it's spreading actively via mosquitos through central and south america, as well as the caribbean. and the threat it poses to reg nant women and unborn babies has health authorities on the hunt for a vaccine. >> we have about five or six candidates lined up to go into vaccine development. >> reporter: sanafee is among drugmakers working on the problem and it may have a leg up. the company has a vaccine for the dengue virus already on the market. that's in the same class of viruses as zika. >> we realized very quickly that it would -- we could take advantage of