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Zika vaccine ‘100% successful in clinical trials on rats’, researchers declare – as they await human results

  • Synthetic DNA vaccine blocked all lab rats from Zika, researchers say
  • The jab also protected infected rats from Zika-related brain damage 
  • It is the first trial to test a vaccine in animals that, like humans, are naturally susceptible to Zika
  • The team is also testing the vaccine in human trials, awaiting results 

Trials of a new Zika vaccine have been 100 percent successful in blocking the virus and its devastating side effects, a report reveals.

The global spread of the disease shows no sign of letting up, and efforts to control it have so far proved futile.

However, the first clinical trial to test Zika-susceptible animals has found that a synthetic DNA vaccine successfully protected the immune system and brain of lab rats in every case.

It is the most promising result of a Zika vaccine to date – and it is the same one being tested in the first human clinical trials.

IOWA CITY, IA - AUGUST 11: Marisa Grunder, 27 of Wilton, Iowa, is given a shot during trials of an H1N1 vaccine, developed by CSL of Australia, at University of Iowa Health Care, the University's medical center, on August 11, 2009 in Iowa City, Iowa. The university's medical center is one of 8 trial sites across the nation conducting human studies on the new vaccine which is looking at optimal dosage levels for a variety of age groups. (Photo by David Greedy/Getty Images)
The first clinical trial to test Zika-susceptible animals has found that a synthetic DNA vaccine successfully protected the immune system and brain of lab rats in every case (Photo by David Greedy/Getty Images)

None of the lab rats in the study in Philadelphia’s Wistar Institute contracted Zika after getting the vaccine.

Those that were infected before being vaccinated were protected from any kind of damage to the brain’s hippocampus and cerebral cortex – Zika’s targets.

‘Our results support the critical importance of immune responses for both preventing infection as well as ameliorating disease caused by the Zika virus,’ said lead researcher Dr David Weiner, director of The Wistar Institute’s vaccine center.

As the threat of Zika continues, these results provide insight into a new aspect of the possibly protective ability of such a vaccine as a preventative approach for Zika infection.’

Previous studies of the Zika vaccines, though often successful, only tested animal models that are naturally resistant to Zika.

Rats, however, have the same immune response to Zika as humans.

According to Dr Weiner, the rat trial results are a promising sign for the human trials.

He and his colleagues observed that the vaccine generated robust antigen-specific antibody and T cell responses that neutralized the virus.

They also found that the vaccine provided protection against the disease and death in animal models.

And it was neuroprotective, blocking the disease from spreading to the brain.

This is especially important given the risk that infants born with the disease have of developing microcephaly, a birth defect resulting in an abnormally small head and that may prevent the brain from developing properly.


Researchers believe the vaccine could protect Zika from infecting the brain, preventing Zika-linked microcephaly in babies

One important aspect of Zika and many other mosquito-borne diseases is that not everyone infected with the virus will actually become ill as a result.

With Zika, only about 20 to 25 percent of individuals with the virus are actually impacted by the disease, according to the CDC.

However, there is no way to know for certain who will be at risk for illness due to the virus, which is why it was crucial for this study to examine how a vaccine would operate in an infected, symptomatic host.

A total of nearly 4,000 cases of Zika infection have been reported in the United States alone, according to the CDC.

Just shy of 200 cases of Zika infection originating within the United States have been reported.

More than 60 countries have reported mosquito-borne transmission of the disease.