AUG 04, 2016 6:05 AM PDT

First Zika Vaccine Trial Underway Amid Florida Outbreak

Zika is inching its way into US territory. The past two weeks marked the first instance of local Zika transmission in the US. In response, health officials are deploying measures to contain the mosquito population in the 150-square-meter area of Miami, Florida. In addition, they are also beginning the first Phase I clinical trials of a Zika vaccine on healthy human volunteers a month ahead of schedule.

Last week, the Centers for Disease Control and Prevention confirmed 4 cases of Zika transmission from a mosquito population in Miami, Florida. This week, 11 addition cases were confirmed, also from the same area.

"New test measurements over the weekend showed a risk of continued active transmission in that area," said CDC Director Tom Frieden. "Because of this finding, we are advising pregnant women not to travel to that area and if they have traveled there on or after June 15 to visit their health care provider for testing."

This unprecedented travel warning is the first to affect travelers within US boundaries. Under simple circumstances, Zika infection can bring no symptoms at all or cause mild cold-like symptoms, such as fever and headaches. However, Zika has been shown to cause microcephaly in fetuses. As such, the Zika warning is most focused on women who are pregnant or thinking about becoming pregnant. Furthermore, since Zika has been shown to be transmitted through semen, men are also at risk for carrying the disease and transmitting it to their partner.

The CDC officials are currently investigating why mosquito control efforts seemingly failed in this small community in Florida. Among the scarier scenarios is that the mosquito population here has become resistant to pesticides, which means that even more aggressive measures have to be used.

NIH begins testing Zika vaccine in humans | Image: NIAID
Meanwhile, in the lab at the National Institute of Health at Bethesda, Maryland, officials are beginning
the first phase of the Zika vaccine in humans. The aim is to test the safety and efficacy of the vaccine to produce an immune response in people. Developed by the National Institute of Allergy and Infectious Diseases (NIAID), the vaccine is made of a plasmid that encode proteins found in Zika. Theoretically, these proteins would trigger a natural immune response that would protect people from getting infected with the real Zika virus.

"A safe and effective vaccine to prevent Zika virus infection and the devastating birth defects it causes is a public health imperative," said NIAID Director Anthony S. Fauci. "NIAID worked expeditiously to ready a vaccine candidate, and results in animal testing have been very encouraging. We are pleased that we are now able to proceed with this initial study in people. Although it will take some time before a vaccine against Zika is commercially available, the launch of this study is an important step forward."

This early phase study is planned for 80 participants in 3 study sites in the US. Though it deployed a month ahead of schedule, results from this trial aren’t expected until late 2016 or early 2017. And even with favorable results, it may still be several years before a Zika vaccine is commercially available.

Until then, officials urge people to avoid travel to Zika hot spots. Elsewhere, people should take precautions against getting bitten by mosquitos in general. This includes covering exposed skin and using mosquito repellent that contains DEET.

Additional sources: NIAID press release, CNN
About the Author
Doctorate (PhD)
I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at
You May Also Like
Loading Comments...
  • See More