WASHINGTON - Researchers are working to get experimental vaccines through the regulatory process and into the hands of people at the center of the Ebola epidemic in West Africa.
But the next phase of an important trial in Mali will not begin until next year.
According to the latest information from the World Health Organization, the number of Ebola cases is doubling every four weeks in Liberia, Guinea and Sierra Leone. This week, the number of Ebola infections in Africa topped 9,000 cases, causing around 4,500 deaths.
Among the hardest hit are health care workers - the WHO now counts 427 workers who have become infected. Of these, 236 have died.
Even though the need is great and researchers are working to get experimental vaccines tested to make sure they are safe for human use, the process can seem frustratingly slow.
A promising vaccine candidate has been tested in a handful of healthcare workers in Mali but won't move into the next phase of human clinical trials until at least early next year, according to Mike Levine, director of the Center for Vaccine Development at the University of Maryland School Of Medicine.
That phase will look at the drug’s safety in a larger group of fifteen health care workers and will also monitor its effectiveness in preventing Ebola, he said.
Levine, who is helping oversee human studies of the experimental vaccine in Mali, said the second phase could serve as a hedge against local spread of the deadly virus by immunizing those who care for Ebola patients.
“If the vaccine is working in humans, like it worked in non-human primates [monkeys], then we may be able to greatly diminish transmission - maybe even interrupt transmission - in localized areas by immunizing contacts of known patients and doing a very good job of immunizing health care workers,” Levine said.
The drug was a hundred percent effective in protecting monkeys against infection with the Ebola virus.
Levine stressed the experimental vaccine, developed by researchers at the U.S. National Institutes of Health, is not a treatment for Ebola. But it may prevent those who have been exposed to the lethal virus from developing full-blown illness.
“One thing we don’t know today is whether, like smallpox vaccine, we can prevent Ebola even though somebody may be two days or three days into the incubation,” according to Levine.
After a second phase of study, Levine said the vaccine will have to undergo a phase III clinical trial in which it’s given to large groups of people to confirm its effectiveness in preparation for regulatory approval.
There’s no prediction on when the final trials are likely to be conducted. At that point, the vaccine trials are expected to include people in Guinea, where the epidemic is out of control.
No cases of Ebola have been reported in neighboring Mali. Once the vaccine undergoes phase III testing, it will be ready for licensing by U.S. regulators, among others.
A second experimental vaccine just began early human safety trials this week at Walter Reed Army Institute of Research in Maryland.