People often ask me about the most difficult assignment I’ve faced in my 29 years at CDC, starting with my arrival as a “disease detective” in 1988, through the five months I served as Acting Director of the agency. While many experiences stand out, a strong contender began in September 2014, when I was asked to organize a field trial of an experimental Ebola vaccine to help battle the West Africa epidemic.
The Ebola virus ultimately killed more than 11,000 people in Guinea, Liberia, and Sierra Leone. And in fall 2014, Ebola cases were increasing exponentially. Flights into the region were being canceled, but CDC was deploying hundreds of staff to the three affected countries. Treatment facilities were scarce and overrun with sick patients, and supplies were limited or non-existent. Humanitarian workers and volunteers infected with Ebola disease were evacuated to Europe or the U.S. and public concerns were raised about double standards for access to experimental treatments.
Candidate vaccines against the virus had been tested in non-human primates and were beginning to be given to small numbers of healthy people in early-stage studies in Europe and the U.S. to assess safety. But even if a candidate product proved safe and effective, there weren’t enough doses of any one candidate to serve the large population that needed it. By October 2014, an NIH-Liberia collaboration was under way to launch a double-blind, randomized controlled trial comparing two experimental Ebola vaccines to placebo, and a WHO-led international consortium was forming to develop a “ring” vaccination study in Guinea, modeled after an approach used for smallpox vaccination. CDC staff headed to Sierra Leone to develop a partnership that eventually became STRIVE – or the Sierra Leone Trial to Introduce a Vaccine Against Ebola.
Our first step was listening to members of the Sierra Leone community, healthcare providers in the field, disease surveillance experts and scientists. Our principles then came together under one overarching goal: to accelerate the introduction and use of an Ebola vaccine among at-risk people, while simultaneously evaluating the vaccine’s safety and efficacy.
The path to accomplishing that goal, however, was far from simple. Outreach to the local stakeholders revealed that some thought that an “Ebola vaccine” meant something that caused Ebola disease. So Sierra Leone trial leaders began to use the phrase “Ebola prevention vaccine” instead. Some thought it was unethical to “try out” an experimental preventive vaccine on West Africans in case the product was risky, wondering if sufficient capacity existed to manage unexpected side effects a vaccine might have. Others thought it wrong to withhold a potentially beneficial vaccine when so many were in desperate need. Meanwhile, people were dying from Ebola virus, including many health care workers who had 100 times the risk of developing the infection. This loss was devastating to a region where healthcare professionals were already scarce. The appropriate pace and the checks and balances for clinical research in this frightening context were murky.
In the midst of planning, we wondered whether the epidemic could be controlled without a vaccination effort. Could human resources in-country and internationally converge to conduct a trial in the midst of a major epidemic that had shut down health care facilities in one of the poorest countries in the world? Would the resources drawn to conduct the trial inadvertently slowdown crucial control efforts?
Ultimately, the communities, health workers, national and international staff – including the 1,400 CDC responders deployed to West Africa – brought the epidemic in the region under control before we could answer the question of vaccine efficacy in Sierra Leone. And we are fortunate that the vaccine we studied (rVSV- ZEBOV) appears to provide substantial short-term protection, based on the novel field trial in Guinea. The STRIVE collaboration has provided the largest safety database available on the vaccine – and the data collected from the trial will form part of the manufacturer’s official submissions that will be reviewed for the product’s application for licensure.
Thanks to long hours of hard work and the development of tremendous partnerships, STRIVE successfully provided an investigational vaccine to about 8,000 Sierra Leonean health care workers and front-line workers who put their lives on the line in Ebola treatment units and district health facilities. Commitment and rapid planning enabled approximately 400 Sierra Leonean nurses, pharmacists, medical students, ambulance teams and technicians to learn good clinical practices and conduct the nation’s first large-scale vaccine trial. Their efforts and experience now leave Sierra Leone better able to tackle the next emerging disease threats and carry out clinical research of regional importance.
CDC’s response to the Ebola epidemic was the largest in our agency’s history, with more than 4,000 staff working on the response worldwide. And we were ultimately transformed by our role in these efforts. We will never forget the intense pressure to deliver, as well as our humility in facing the devastating virus. We take pride in the partnerships that were developed, and yet respect the fragility of the successes. We remember those lost and understand the need for longer-term solutions so that every country can find, stop and prevent epidemics before they reach that scale.
For the next year, we’re hosting a new exhibit about the West Africa Ebola epidemic at the David J. Sencer CDC Museum at our Atlanta headquarters. Introduced by a timeline of events, the exhibit explores the early days of the outbreak, the heroic work of West African and international health workers, and an introspective look at “lessons learned” by CDC and our partners. Visitors will also see artifacts from the epidemic, such as personal protective equipment, and hear first-person audio testimonials from those on the front lines.
There is much more to do to protect each country – and the world as a whole – from this type of public health emergency. We hope the museum exhibit helps us continue to learn from the past and renew interest on health security for the future.
