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Initial reports of a highly effective Ebola vaccine trial may provide the final piece to douse the simmering, historic outbreak in West Africa. Using the technique that eradicated the scourge of smallpox from the wild, an international research team put a “ring” around new cases in Guinea by tracking down and immunizing their contacts.
“While the vaccine up to now shows 100% efficacy in individuals, more conclusive evidence is needed on its capacity to protect populations through what is called ‘herd immunity,’ the WHO reports. “To that end, the Guinean national regulatory authority and ethics review committee have approved continuation of the trial.”
As the outbreak escalated and overran containment efforts last year, some questioned why vaccine development wasn’t begun after the deadly virus first emerged in 1976 in the Congo near the river that shares its name. “There was no way for pharmaceutical companies to profit and our NIH budget had been cut, it has not been a priority for researchers — as if the lives of Africans did not matter,” says Walter Tsou, MD, MPH, a professor of health policy at the Center for Public Health Initiatives at the University of Pennsylvania in Philadelphia.
The new VSV-EBOV vaccine was developed by the Public Health Agency of Canada. The vaccine was licensed to NewLink Genetics Corp, and on November 24, 2014, the company entered into an exclusive agreement with Merck & Co., which assumed responsibility to research, develop, manufacture, and distribute the investigational vaccine. In addition to other financial support, the project was funded by the Canadian and U.S. governments. After safety trials in primates and a small group of human volunteers who were monitored constantly, the vaccine trial began last March and now includes some 4,000 contacts of 100 Ebola cases.
One arm of the research is being conducted by the international Médecins Sans Frontières (MSF, aka Doctors without Borders) group, which has administered the trial Ebola vaccine to 1,200 of its frontline workers in Guinea, including doctors, nurses, paramedics, laboratory staff, cleaning staff, and burial teams.
“These results are promising and we should definitely make this vaccine available to at-risk groups as soon as possible,” the group said in a statement posted on its website. “But it is also of crucial importance to keep working on all the pillars of an Ebola response including contact tracing, health promotion, and isolation of infected patients.”
Patient isolation will still be critical because it would be frankly incredible if the vaccine showed a 100% efficacy over time. In addition, even immunized workers will have to take care not to expose patients and unvaccinated colleagues to blood and fluid contamination on their protective gear.
During the Ebola outbreak in West Africa that is now making its last stand, 510 healthcare workers have given their lives trying to save others. The deaths translate to a mortality rate of 58% of the 880 healthcare workers infected as of July 26, 2015, the WHO reports. As of that date, the outbreak case count had climbed to 27,748 cases with 11,279 reported deaths, the WHO reported.
Factors cited by the WHO for the occupational Ebola infections include shortages of personal protective equipment, improper use of PPE, and for much of the outbreak, far too few medical staff for the overwhelming number of cases. In such circumstances, healthcare workers demonstrate a compassion that contributes to working in isolation wards far beyond the number of hours recommended as safe, the WHO notes.
With a few exceptions — like some of the U.S. healthcare workers — many of the infected caregivers were treated under the very conditions of the epidemic they were fighting, making it difficult to deliver the full measure of care needed. Consider that the two deaths among the 10 cases treated in the U.S. translates to a mortality rate of 20%, suggesting that part of the reason Ebola is so deadly in Africa is that the level of patient care demanded cannot be adequately delivered.