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Testing Begins On An Experimental Zika Vaccine With Inactivated Virus

Federal scientists have launched another test in human volunteers of a Zika vaccine. This one uses a more traditional approach than an experiment that started in August.

Federal officials are eager to develop a vaccine as quickly as possible, which is why they are pursuing multiple approaches. This experimental vaccine, called ZPIV, has already proved effective when designed to target a virus similar to Zika, called Japanese encephalitis.

"We urgently need a safe and effective vaccine to protect people from Zika virus infection, as the virus continues to spread and cause serious public health consequences, particularly for pregnant women and their babies," Dr. Anthony Fauci said in a statement Monday. He heads the National Institute of Allergy and Infectious Diseases (NIAID), which is funding the research along with the Department of Defense.

Researchers at the Walter Reed Army Institute of Research in Silver Spring, Md., are recruiting 75 volunteers to test the vaccine. Researchers will monitor them to make sure the vaccine is safe. They want to find out whether people injected with the vaccine will produce antibodies that will protect them from the disease.

The vaccine has already been tested in monkeys, where it proved effective against Zika.

ZPIV uses a strategy that has worked in many other vaccines: scientists cripple the virus so it can't cause disease, but that inactivated form still triggers an immune reaction. Vaccines for polio and flu are two examples of inactivated vaccines.

In August, NIAID started testing a less traditional vaccine for Zika. That vaccine uses a small, circular piece of DNA that is injected into a person's arm. That DNA directs cells in the human body to produce Zika-like proteins, which in turn trigger an immune response. This techniquewas first used for developing a vaccine for the West Nile virus, but it's not yet on the market.

If that vaccine proves to be promising, federal researchers hope to expand trials of it in countries where Zika is prevalent in early 2017.

The World Health Organization says Zika has been identified in 73 nations as of Nov. 3. That includes the United States. The CDC reports about 4,000 cases in the continental United Sates and Hawaii, including 139 cases among people who acquired the disease domestically. More than 30,000 cases have been diagnosed in Puerto Rico.

Zika occasionally causes severe brain damage in children born to women who are infected with the virus while pregnant. Some people also experience a rare nervous system disorder called Guillian-Barre syndrome.

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Award-winning journalist Richard Harris has reported on a wide range of topics in science, medicine and the environment since he joined NPR in 1986. In early 2014, his focus shifted from an emphasis on climate change and the environment to biomedical research.