In February 2016, the World Health Organization (WHO) declared the mosquito-borne Zika virus a global threat. Although the Zika virus only causes mild symptoms in most people, it is suspected to cause microcephaly, a birth defect that results in babies being born with underdeveloped brains. There is also some evidence of a link between Zika and Guillan-Barré syndrome, a disease in which the immune system attacks the nervous system, causing muscle weakness and breathing problems.
According to the WHO, approximately 15 companies around the world are currently trying to develop Zika vaccine candidates in response to the possible threat of this virus. Large-scale trials are not expected to begin for another 18 months. The process to develop and approve a vaccine for human use is typically a slow one, since vaccine candidates must go through rounds of animal testing, followed by human volunteer testing. It can often take years or even decades to release a new vaccine.
The Vaccine Research Center at the National Institute of Allergy and Infectious Diseases is hoping to speed up the usual vaccine development timeline. They are currently creating different versions of a DNA-based vaccine and testing them in animals to determine the top candidate. Some researchers would like to give human volunteers a promising candidate vaccine and later inject the volunteers with the Zika virus in order to quickly find out if the vaccine is effective. However, this approach may not be safe, especially if scientists determine that there is a link between Zika and Guillan-Barré syndrome, as well as Zika and microcephaly.
Zika Virus Spread
Some researchers also hope to use what we know about dengue and West Nile, two other mosquito-transmitted viruses, to develop a Zika vaccine more quickly. Because Zika is similar to these two viruses, some scientists believe it may be possible to swap Zika DNA into experimental dengue and West Nile vaccines that have already been created. If successful, this could considerably shorten the time it takes to approve and distribute a vaccine.
While the search for a virus continues, epidemiologists are reviewing available data about Zika outbreaks and cases of microcephaly, microbiologists are studying the way the virus affects cells in animal subjects, and diagnosticians are working to develop more reliable tests for identifying past and present Zika infections. While there are many things about the Zika virus that we still don’t know, scientists in many different fields are collaborating in an effort to find answers.