Volunteers sign up for Ebola vaccine trial at UM School of Medicine

Twenty people walking around Baltimore are silently building immunity to Ebola.

Two years ago, Khandra Sears contracted malaria for the good of science. Two weeks ago, the 33-year-old postdoctoral fellow became a test subject in research to stop another scourge: Ebola.

She was injected with 100 billion particles of a chimpanzee cold virus that had been modified to resemble Ebola. Over the next year, she will give researchers copious amounts of her blood to test for antibodies that could disable the Ebola virus.

On a recent visit, her body just wouldn't bleed anymore. She couldn't fill the ninth and final vial researchers sought to fill.

But for Sears and many of the other volunteers, the sacrifice is worth it. She is among 20 research subjects who have received the experimental Ebola vaccine in a study at the University of Maryland School of Medicine over the past two weeks.

Many are medical researchers of some type themselves. They understand that their discomfort could save lives.

"This was a way I could help," said Sears, who will receive up to $1,000 for her participation. "Vaccine development is such an important process to take part in."

The Baltimore trial is one of several testing the safety and effectiveness of the vaccine, which is one of many candidates that is being ushered through clinical trials in hope of ending the Ebola outbreak that has killed more than 5,000 people in three West African countries since December. Researchers are eager to study the effect the vaccine has on Sears and the other volunteers because ethically, they cannot expose anyone to Ebola to test how they would respond.

The vaccine cannot give the subjects Ebola. It contains proteins that fool the immune system into mistaking the harmless chimpanzee virus for Ebola.

But that doesn't stop friends and family from being concerned for the volunteers. Andrea Buchwald, a 28-year-old doctoral student in epidemiology who also received the vaccine, said people she has told have assumed she's putting herself at risk by participating. As an epidemiologist, she said, she sees that as an opportunity to help others learn more about vaccine development.

"I allowed myself to be given this experimental vaccine because I have that much confidence in the process that led up to the development of it," Buchwald said. "There's a lot of testing that happens beforehand."

That doesn't mean the process is painless. As with the flu shot or other inoculations, the Ebola vaccine caused some side effects in some of the participants, said Kirsten Lyke, an associate professor of medicine who is working on the study. Buchwald said she came down with a fever of nearly 101 degrees hours after the vaccination, and both she and Sears said it left them exhausted.

The researchers gave half the participants a dose containing 10 billion particles, and the other half a dose with 10 times as many particles. Buchwald and Sears said they received the higher dose. The method helps researchers learn how much vaccine a patient needs to create immunity, and how long that immunity lasts.

Researchers at the National Institutes of Health, who developed the vaccine along with drugmaker GlaxoSmithKline, plan to compare the subjects' immune response with that of monkeys who were given the vaccine and then exposed to the virus.

Researchers can make inferences based on what they see in the subjects' blood, but because they are ethically barred from exposing humans to Ebola, they won't know for sure whether they have developed immunity.

That restriction applies to each of the handful of Ebola vaccine candidates being tested.

"Unless you have a crystal ball that is well maintained, you can't really predict how any of these things will perform in humans," said Nancy Sullivan, chief of the biodefense research section of the NIH's National institute of Allergy and Infectious Diseases. "It's cautious optimism."

Despite the risks and potential for discomfort for the volunteers, the medical school's Center for Vaccine Development received an unusually eager response from participants, Lyke said. The study paid a typical rate to test subjects. Buchwald said she received $150 for being vaccinated and will receive another $50 each time her blood is drawn.

"Typically, we get one or two people here and there throughout the week, not 120 in three days," Lyke said. "That was a nice positive response."

The increased concern over Ebola has given researchers new opportunities to advance their vaccine work.

Before the outbreak, they had difficulty persuading investors to back their vaccine candidates. The virus typically appeared in relatively small, isolated populations. But with more deaths in the current outbreak than in all previous outbreaks combined — and fears of the virus spreading around the globe — vaccine candidates have risen on the pharmaceutical companies' priority lists.

Baltimore biotechnology company Profectus BioSciences has received $32 million from U.S. government agencies this year to speed its development of Ebola vaccines. The company has been working for years on vaccine candidates but had faced difficulty raising money to pay for human trials. Executives expect to start the trials next year.

Pharmaceutical giant Merck & Co. Inc. gave another promising candidate a boost this week when it said it would buy worldwide commercial rights to the Ebola vaccine developed by Canada's Public Health Agency. Merck is paying NewLink Genetics Corp., based in Ames, Iowa, $50 million for the rights. A NewLink subsidiary licensed the vaccine from the Canadian government in 2010.

The Securities and Exchange Commission cautioned investors last week who might be eager to get in on the booming market for Ebola vaccines and treatments. The SEC suspended trading in four small companies that it said had made unverifiable claims about products to prevent or treat the deadly virus.

The Baltimore volunteers are among more than 200 people who have received a vaccine candidate developed at the National Institute of Allergy and Infectious Diseases, which is part of the National Institutes of Health, in collaboration with GlaxoSmithKline. A pilot study of the vaccine involving human subjects was conducted at the NIH in September. Since then, more trials have begun at the University Hospital of Lausanne in Switzerland, the University of Oxford, Emory University Hospital in Atlanta and among health workers in Mali.

The University of Maryland's Center for Vaccine Development is working with a sister organization in Mali on those trials, in partnership with that country's health ministry.

So far, the trials have shown promise, Lyke said, with no significant safety concerns raised. Preliminary results from the NIH pilot study are expected to be published soon.

Sears said that participating in clinical trials has given her a better understanding of what goes into solving some of the world's worst epidemics. In 2012, she participated in a study that helped show how much exposure to malaria it takes to cause infection — information that eventually could be used in clinical trials of vaccines for that disease.

It also helped improve diagnostics for detecting malaria, she said.

"You just get a better idea of the research involved in developing these vaccines and what's required," she said. "You realize they are really long-term projects."

And they are projects that rely on those willing to be the lab rat.

"It's a really cool way to be able to contribute to a really important public health effort," Buchwald said.

Reuters contributed to this article.

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