An experimental Ebola vaccine produced by GlaxoSmithKline haven’t revealed any side affects during the first stage of testing and produced an immune response in all 20 healthy volunteers who took part in the trial, scientists reported on Wednesday in the New England Journal of Medicine.
The testing, which started on Sept. 2 and is scheduled to monitor the volunteers for 48 weeks, is expected to show how safe the vaccine is. However, the immune response suggests that it would also be effective.
“The safety profile is encouraging, as is the finding that the higher dose of vaccine induced an immune response quite comparable to that which has completely protected (lab) animals from Ebola,” said Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID), which is conducting the trial in Bethesda, Maryland.
“It’s good news. If it was very toxic or didn’t induce good immune response, we couldn’t go on to the next step, but the proof of the pudding is efficacy,” he added.
“The intramuscular vaccine was developed at NIAID and Okairos, a biotechnology company acquired by GlaxoSmithKline. It contains genetic material from two Ebola strains – Zaire, responsible for the current outbreak in West Africa, and Sudan – but no virus, so it cannot cause the disease,” explains Reuters.
As the medicine is unethical to expose volunteers to the deadly virus, researchers assess the effectiveness of candidate vaccines by whether they trigger production of anti-Ebola antibodies and immune-system T cells.
For testing of the potential cure 20 volunteers ages 18 to 50 were selected. Half received a lower dose and half a higher dose. All 20 developed anti-Ebola antibodies within four weeks, with those on the higher dose producing more.
“Dose also affected production of T cells; seven of 10 people on the high dose produced one crucial kind of T cell, but only two on the low dose did. The higher the dose required to trigger immunity, the more challenging and expensive it will be to produce large quantities of vaccine, manufacturers say,” Reuters says.
The results show that the higher dose should be used, said Fauci by telephone.
“We are very encouraged by these positive first trial results,” Moncef Slaoui, Glaxo’s chairman of global vaccines, said in a statement. “It’s important to remember that these data are the first piece in the jigsaw and we’re continuing to gather other important information.”
An efficacy trial involving thousands of patients will start in Liberia in January, said Fauci. The subjects will receive either a placebo, NewLink’s vaccine, or Glaxo’s, and infection rates in the three groups will be compared to determine which works best.
In the meantime, additional safety trials of Glaxo’s vaccine are running in Switzerland, the U.K. and Mali, according to the U.S. National Institutes of Health.