healthHealth and Medicine

Experimental Zika Vaccine To Begin Human Trials


Robin Andrews

Science & Policy Writer

Brazil has seen many thousands of cases of Zika-related microcephaly in newborns in the last few months alone. Mario Tama/Getty Images

Zika continues to spread across the world, and many are rightfully worried about its proliferation across the Northern Hemisphere during the upcoming summer months. However, scientists may be about to add a powerful weapon to their arsenal in the fight against the virus: The first experimental Zika vaccine to be tested on humans is expected to be deployed in the next few weeks.

As reported by the Guardian, the pharmaceutical company Inovio have just received approval from the US-based Food and Drug Administration (FDA) to commence a small clinical trial. The company plans to test the vaccine on 40 healthy human adults, and represents “phase one” of testing – researchers will look at the body’s immune response to the vaccine first and foremost.


“As of May 2016, 58 countries and territories reported continuing mosquito-borne transmission of the Zika virus; the incidences of viral infection and medical conditions caused by the virus are expanding, not contracting,” Inovio’s president and CEO, Dr J. Joseph Kim, said in a statement. “We are proud to have attained the approval to initiate the first Zika vaccine study in human volunteers.”

An illustration of the Zika virus. AuntSpray/Shutterstock

GLS-5700, as the experimental dosage is dubbed, contains synthetic segments of Zika viral DNA, which the body will hopefully see as a threat and kick-start an immune system response in order to isolate and destroy it. Although not yet confirmed by the FDA, Inovio say that this is the first DNA vaccine approved for use in humans in the US. It has already been tested on small and large animals, but in order to truly test its effectiveness, human participants are, as always, required.

Most vaccines are produced through a process known as “live attenuation”, wherein cultures of the pathogen are grown before being subsequently weakened to the point wherein it is safe to give to a person in order to provoke a powerful immune response.


A DNA vaccine, a relatively recent invention, involves directly administering genetically engineered DNA – based on the virus’ RNA – straight into the person, whose immune system will immediately recognize as containing hostile molecules of infection (“antigens”) and produce antibodies to it in response.

The advantages of DNA vaccines are that they are more stable than their attenuation counterparts, and the immune response triggered involves multiple types of white blood cells. Although initially effective, researchers have yet to demonstrate that they provide the same long-term immunity that attenuation vaccines feature.

Unfortunately, this new vaccine, if successful in phase one trials, will still not be on the market in the near future. Making sure a vaccine is completely safe to administer takes considerable lengths of time, and as the prime candidates are pregnant women, future trials will have to be particularly robust.

Rio, Brazil, is the epicenter of the viral outbreak, and the Olympics are due to take place there this summer. It's a bad combination. f11photo/Shutterstock


The Zika virus has been out of the news for a month or so, but global health officials remain deeply concerned about it. It currently has no cure, it has been conclusively shown to cause microcephaly in newborns, and it has a propensity towards destroying neurons. Its central pooling of cases remains highest, by far, in the state that is hosting the Summer Olympics this year, and many are calling for them to be moved or canceled in order to prevent a “full-blown global health disaster.”

This vaccine may prove to be a welcome step, but there’s a long way to go before the tide will turn against the Zika pandemic.


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