University of Minnesota researchers are injecting Liberians with defective strains of live Ebola as part of a trial for a new vaccine.

Researchers plan to test two vaccines — a live strain and a dead strain of the virus — along with a placebo, in hopes of discovering an immunization that works.

They began the trial two weeks ago and estimate the new vaccines, which were developed by two pharmaceutical companies, will take about a year to test, depending on the progression of the Ebola epidemic.

The National Institutes of Health chose biostatisticians from the University of Minnesota’s School of Public Health to design the trial, collect data and analyze the results. The NIH is funding and supervising the project, which has scientists working with the University researchers in Liberia, called the Partnership for Research on Ebola Vaccines in Liberia.

The trial is a double-blind study, which means neither the researchers nor participants know which of the three options are being used in each injection.

University biostatistics professor and researcher on the project Cavan Reilly said the study’s participants are randomly assigned to one of three test groups, which is important in keeping the study objective.

“By randomizing people, we can more easily assess the effect of the vaccine on someone’s downstream health outcomes,” he said.

Researchers will closely monitor the patients at the injection site for serious complications, like a rash, and any type of need for hospitalization, Reilly said.

Researchers give prospective patients resources that explain the trial and thoroughly discuss its specifics before the participants sign a consent form, said Jim Neaton, a University biostatistics professor and project leader.

Over the next several months, the trial will enroll approximately 27,000 participants, with about 9,000 in each test group.

The vaccines’ effectiveness will be determined after researchers analyze which participants contracted the disease, if any.

If both the group given the placebo and one of the groups that received the vaccine contract Ebola, and the other group that was vaccinated does not, researchers can conclude the second vaccine is effective.

The NIH chose the pharmaceutical companies based on how fast and effectively they responded to the request for two vaccines, Neaton said.

“The preliminary evidence suggests they both generate an immune response,”Neaton said. “We could have two effective vaccines based on this study, but time will tell.”

The companies tested the drugs on animals first and then on healthy humans in the U.S. and Europe, Reilly said.

He said the trial would immediately stop if one vaccine works — or if neither do.

Reilly said the Liberian government will choose a vaccine to purchase based on the study’s results.

And as the Ebola epidemic begins to decline, researchers will have to make some changes to their trial, according to an NIH press release.

But if the study goes as planned, NIH and SPH officials plan to create a treatment trial in search of an Ebola cure.

Reilly, who worked on HIV trials for 15 years before joining the trial team, said he is optimistic about the results.

“I hope we find that there’s at least one effective vaccine that stops Ebola,” he said.