The U.S. National Institutes of Health (NIH) has begun its clinical testing of an experimental vaccine designed to protect individuals from the dreaded effects of the Zika infection.

According to the federal health agency, the early-stage trial is designed to find out the safety of the vaccine candidate, as well as its ability to generate a response from the immune system of study participants.

As many as 80 participants, between the ages of 18 to 35 years old, were selected to take part in the trial, which will be conducted in various sites around the country, including the NIH's clinical center in Maryland.

The experimental vaccine was developed earlier this year by experts at the National Institute of Allergy and Infectious Diseases's (NIAID) Vaccine Research Center.

Dr. Anthony S. Fauci, director of NIAID, said creating a safe and effective Zika virus vaccine is a public health priority. He said that the agency has worked hard to ready the experimental vaccine, and that the testing on animals shows encouraging results.

While it will still take some time before the new drug becomes available commercially, Fauci said the launch of the clinical testing on humans is a crucial step forward for its development.

The NIH said the testing approach used for the experimental drug, known as NIAID Zika virus investigational DNA vaccine, shares similarities with those used to create another vaccine candidate for the West Nile virus (WNV). The WNV vaccine candidate was shown to be safe to use on humans and to trigger an immune system response when it was tested during a Phase 1 trial.

Fight Against Zika Virus Spread

The development and testing of the vaccine candidate are considered to be part of the federal government's response to prevent the spread of the Zika virus in the country.

Data from the Centers for Disease Control and Prevention (CDC) show that as many 50 different countries and territories around the world have recorded cases of active Zika transmission. In the U.S. alone, about 6,400 Zika virus infection cases have already been reported.

Not all patients infected with the Zika virus show signs or symptoms of the disease. Those that do, however, only experience mild illness, which often lasts for about a week.

The more serious impact of Zika infection is often seen on pregnant women, whose unborn child can suffer from a severe birth defect known as microcephaly. This condition can cause the child to be born with an abnormally sized head as well as other brain and organ problems.

As of the moment, there is still no confirmed drug to cure Zika infection or vaccine to prevent its spread.