WASHINGTON — Scientists at the Walter Reed Army Institute of Research started vaccinations in the first clinical trial to test the safety and immune response in people of a vaccine candidate to prevent Middle East respiratory syndrome, known as MERS.
A MERS vaccine would be an important medical countermeasure for U.S. troops in the Middle East and wherever the virus might arise, officials said.
MERS is a severe respiratory disease similar to severe acute respiratory syndrome, or SARS. Both are coronaviruses. MERS was first identified in Saudi Arabia in 2012 and has since infected more than 1,600 people.
The coronavirus kills about 40 percent of those infected, principal investigator Dr. Kayvon Modjarrad told DoD News in a telephone interview, "so low prevalence doesn't mean low risk."
Modjarrad is associate director for the Emerging Infectious Disease Research Program at WRAIR.
The virus circulates mainly in Saudi Arabia, where most cases have been reported, he said. But the World Health Organization reports that MERS cases infected in the Middle East and exported outside the region have been confirmed in 26 countries, including two in the United States. And last year, South Korea had the largest outbreak outside the Middle East, Modjarrad added.
With about 35,000 U.S. troops on the ground in Middle East countries that make up U.S. Central Command's area of responsibility and more than 27,000 in South Korea, a MERS vaccine would be an important countermeasure for the Defense Department, the infectious disease specialist said.
The most common MERS symptoms are fever, cough and shortness of breath. Older people and those with weakened immune systems are at greater risk for severe disease and death. There are no approved MERS vaccines or specific treatments, according to WRAIR.
First Clinical Trial
"This is a really important step that we've taken to initiate a Phase I trial for MERS, and I'm hopeful that this will inform studies to follow. But I can't say exactly when we expect to have a MERS vaccine ready for licensing," he said.
Other vaccine candidates have been tested for use in camels, the likely source of the coronavirus that causes MERS, but this vaccine candidate is the first to be tested in people, a WRAIR news release said.
Seventy-five participants will receive the vaccine at WRAIR's Clinical Trial Center in Silver Spring, Maryland. The vaccine, called GLS-5300, is being co-developed by Inovio Pharmaceuticals and GeneOne Life Science Inc.
"Along with the development of countermeasures, we really need to understand the epidemiology and the pathogenesis of this virus better," Modjarrad said, adding that scientists are sure camels are the reservoir for MERS, and that there has been limited person-to-person transmission.
"Having said that," he added, "the whole South Korean outbreak was all human to human."
One person went back to South Korea from the Saudi Arabian peninsula and infected another 80 people and then eventually, through person-to-person contact, 186 people got infected with this virus, Modjarrad said.
"So there's a great risk that [MERS] could cause major outbreaks even in settings where there are no camels," he said.
MERS DNA Vaccine
Modjarrad said the MERS vaccine being tested is a DNA vaccine.
"One of the benefits of a DNA vaccine is that you don't need any kind of culture system, like eggs, and you can produce it very quickly," he explained. "That's why we have a vaccine so quickly, because we have a backbone that has been used for other types of vaccines."
In the GLS-5300 vaccine candidate, the DNA has part of the MERS virus, but it goes into a larger backbone that has been used for other kinds of vaccines, including those for influenza, human papilloma virus and Ebola virus, he added.
Global Health Landscape
DNA technology will shorten the time it takes to produce and ramp up the vaccine once it's been approved by the Food and Drug Administration, Modjarrad said, and the Ebola outbreak in West Africa also plays a part in shortening the time it takes to get the vaccine to patients.
"The landscape of global health and of research and development for vaccines and therapeutics has changed in the post-Ebola world," he said. "The Ebola outbreak mobilized the global community in terms of resources and political will to get things moving along faster timelines than would never, ever have been possible or even conceived before."