Swiss researchers have temporarily halted a clinical trial of a Canadian-made Ebola vaccine after seeing an unexpected side-effect in a few people who received the serum.
Four of 59 people vaccinated so far in the Geneva-based trial reported pain in the joints of their extremities - fingers and toes - between 10 and 15 days after receiving the shot, researcher Dr. Angela Huttner said in an interview.
While the symptoms were mild, the team wanted to take some time to see what is going on before injecting additional volunteers, Huttner said.
“The reason we want to hold just for a few weeks is because this wasn't expected. The other sites aren't seeing this. We just want to know what's going on before we do any more injections,” she said.
Several other trials are underway of this vaccine, designed by scientists at Canada's National Microbiology Laboratory in Winnipeg and donated to the World Health Organization by the Canadian government.
It is also currently being tested at the U.S. National Institutes of Health, the Walter Reed Army Institute of Research, in Bethesda, Md., and at Dalhousie University in Halifax.
The licence for the vaccine was recently acquired by pharmaceutical giant Merck from NewLink Genetics, a small Iowa-based biotech company that had been developing the vaccine.
In some clinical trials volunteers receive either an active drug of vaccine or a placebo. But Huttner said it is known that all four reporting joint pain in this trial received vaccine.
Three received the lower of two doses being tested in Geneva; the dose received by the fourth is not known because that person is in a “blinded” part of the trial, where researchers will only learn after they analyze the trial's results which dose he or she received.
The trial is schedule to resume on Jan. 5, the University Hospitals of Geneva - where the research is taking place - said in a press release.
Huttner said none of the four who experienced the side-effect has serious illness.
“I can tell you they are all doing really well. These are people who are working. They're functioning just fine. These are very minor finding,” she said.
“In fact, in almost all of the cases they came for their scheduled visits. They didn't call us urgently. These were things that we picked up.”
Huttner, who is an infectious diseases specialist, said people can experience joint pain after having a viral infection and after receiving some vaccines. It is commonly seen in women who are vaccinated against rubella, she said.
She said the team thinks this side-effect is likely an acceptable one, but wants to see how common it is and how severe it might be. A number of the people who have received the vaccine in this trial are not yet at day 15 after their vaccination.