West African Ebola vaccine trials to start soon

U.S. scientists will begin the first large-scale tests of Ebola vaccine on people in West Africa within a few weeks, officials announced Thursday.

Scientists at the National Institutes of Health will partner with the Liberian government to launch a clinical trial of two vaccines, one developed in the USA and one developed in Canada, said Anthony Fauci, director of the National Institute of Allergy and Infectious Disease.

Researchers at the Centers for Disease Control and Prevention will work with the government of Sierra Leone to test one of the vaccines.

An effective Ebola vaccine could be lifesaving in future outbreaks and could help to control the current outbreak, Fauci said.

Beyond vaccines, NIH doctors will work with Liberia to test the experimental treatment drug ZMapp, which has been given to several Ebola patients but has never been formally tested in humans. The studies will be conducted in the USA and Liberia.

Ebola has infected 21,759 people and killed 8,668, primarily in Guinea, Liberia and Sierra Leone, according to the World Health Organization.

It has devastated the three countries' health care systems, which were already fragile. At least 838 health workers have been infected, and 499 have died from Ebola, the WHO says.

Public health measures such as making sure bodies are buried safely have helped to drive down the number of new cases in all three countries.

In Liberia, doctors diagnose eight cases a week, compared with 300 a week in August, the peak of the outbreak, the WHO says.

Cases are also falling in Sierra Leone, the hardest-hit country. There were 117 new Ebola cases in the week that ended Jan. 18, compared with 184 cases the previous week and 248 cases the week before that, according to the WHO.

Though that's good news for patients, the falling number of cases could make it harder to test new vaccines, said Michael Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota.

That's because it could take longer to detect a difference between the Ebola infection rates among people who got the vaccine and those given a placebo, Osterholm said. Researchers need to enroll many people in the clinical trial, then wait until a certain number either get sick or appear Ebola-free. Doctors can reach that critical number quickly during a raging outbreak, when new patients are diagnosed every day. When cases are few, doctors may have to wait much longer to observe a difference between vaccinated and unvaccinated patients.

"When you have so few cases, it gets very hard to show that vaccines work," Osterholm said.

If U.S. scientists can't find enough people to enroll in Liberia, they may reach out to Sierra Leone, asking if that country would like to join, Fauci said.

Fauci noted that scientists will get a lot of data from vaccine trials, even if the number of Ebola cases continues to fall. Scientists can study the vaccines' safety and measure whether they stimulate the immune system.

Fauci said the companies developing the Ebola vaccines, GlaxoSmithKline and Merck, could apply for Food and Drug Administration approval, despite the limited data, through a special process for highly lethal diseases, such as Ebola, for which there are no other treatments or drugs.

In other news, a health worker was released from the Nebraska Medical Center in Omaha after being monitored for three weeks because of a high-risk exposure to Ebola. The patient never became sick or tested positive for Ebola.

The patient, who asked not to be identified, released a statement saying, "The hardest part of the last few weeks was leaving my patients in Sierra Leone, who were some of the sickest I have ever seen. I hope to return to West Africa to help in the fight against Ebola."