The link between microcephaly in unborn children and Zika hasn’t been definitely confirmed, but vaccine development is a top priority. Percio Campos/EPA February 2, 2016 Here’s why we don’t have a vaccine for Zika (and other mosquito-borne viruses) Suresh Mahalingam, Griffith University and Michael Rolph, Griffith University As Zika fear rises, people are inevitably asking why we don't have a vaccine to protect against the mosquito-borne virus.