The Food and Drug Administration on Monday for the first time approved a clinical trial for an experimental vaccine for Zika virus, an early but significant step in the effort to combat a disease that has quickly emerged as a global health threat.

The vaccine, whose working name is GLS-5700, is made by Inovio Pharmaceuticals of Plymouth Meeting, Pa., and GeneOne Life Science, of Seoul, South Korea. The companies said they expect to begin their first tests in humans within the next few weeks.

"We are proud to have attained the approval to initiate the first Zika vaccine study in human volunteers," Inovio's president and CEO, Dr. Joseph Kim, said in a statement.

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Interim results from the testing, which will involve 40 healthy adults, are expected later this year. Testing in a variety animal models has shown the vaccine triggered what Inovio called a robust antibody response.

So-called Phase 1 trials don't reveal if a product works, but they can provide hints. These small trials are designed to determine whether a product is safe to administer to people and to determine the effective dosage.

The move to quickly test a Zika vaccine reflects a sense of urgency surrounding efforts to develop a vaccine. But if this — or any other experimental Zika vaccine — looks promising, there are still several years of testing and development work ahead before patients could head to their doctors' offices to get a protective shot.