The Centers for Disease Control and Prevention is looking to enroll 6,000 people in an Ebola vaccine trial now underway in Sierra Leone.
Frontline workers are being randomized to the experimental vaccine rVSV-ZEBOV either up front or 6 months after enrollment. Subjects then will be followed for 6 months to see how well the vaccine protects them from infection. The trial will cost about $25 million, funded mostly by the U.S. government.
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“The Ebola epidemic has been devastating for West Africa. I really hope that this is the beginning of a new positive chapter for Sierra Leone and the story of battling this virus,” said Dr. Anne Schuchat, director of CDC’s National Center for Immunization and Respiratory Diseases.
So far, about 200 people have enrolled in the study, and more than 90 have gotten the shot. Foreign aid workers are eligible for the trial, but because subjects need to be in country long enough for follow-up, most will be from Sierra Leone. To cover time and transportation costs, participants are paid $10 for enrollment and $30 after they get the vaccine, Dr. Schuchat said in an April 14 teleconference.
Subjects include doctors, nurses, janitors, lab technicians, security guards, pharmacists, administrators, burial workers, and those who wash the bodies of the newly dead. The study is being conducted in hard-hit areas of Sierra Leone, including the capital of Freetown. Similar studies are underway in Liberia and Guinea.
Ebola cases “are way down” in West Africa lately, “but people are continuing to get” the disease, “and some of the Ebola outbreaks in the past have had long tails,” so health care workers remain at risk, according to Dr. Schuchat.
With infection rates down, it’s unclear whether or not the study will have enough cases to demonstrate efficacy for rVSV-ZEBOV. Even so, “we plan to collect information on safety and immune response that could contribute to licensure pathways even if we are not able to estimate efficacy,” she said.
About 800 people have gotten rVSV-ZEBOV in other trials. Common side effects include fatigue, fever, headaches, and muscle aches. There have also been reports of mild, self-limited joint pain and swelling.
CDC is working with the Sierra Leone College of Medicine and Allied Health Sciences and the Sierra Leone Ministry of Health and Sanitation to conduct the trial, dubbed The Sierra Leone Trial to Introduce a Vaccine against Ebola (STRIVE). About 350 local people have been hired and trained to help with the study.
The vaccine uses a vesicular stomatitis virus carrying a noninfectious Ebola virus gene, and has been shown to produce an immune response against the virus. It was developed by the Public Health Agency of Canada’s National Microbiology Laboratory and is licensed to NewLink Genetics. In 2014, NewLink entered into a licensing and collaboration agreement with Merck to develop rVSV-ZEBOV.
Until it is known whether or not the vaccine works, and how well, CDC cautioned that vaccinated people still need to take full protective measures against Ebola.