let me start and dr. zahn mentioned we are a couple of years away from a vaccine in your work shows that a vaccine should work though, correct? >> correct. >> what is the stumbling block? we can develop a vaccine quickly with those viruses. is there a vaccine right now for dengue fever by chance? >> there is a vaccine is partially effective for dengue and some mint advanced testing. hiv scientist on my says that to make full predictions about vaccines but in this case there are lots of biological reasons why should be fairly straightforward to make his zika virus vaccine and why such a vaccine should be feasible and should work. some work that came out of dam baruk's group showed the same concepts that they used to deploy vaccines to other diseases shows effectiveness in my so again we have lots of reasons to think of vaccine is feasible however the vaccine still need to be tested first for safety and small numbers of people and then they need to be tested in small efficacy trials and finally they need to be t