Researchers will have to follow patients who are treated with the new drugs, as well. It's still not clear if the Ebola virus persists in hidden parts of patients' bodies, even after they look healthy, Kindrachuk says. In Ebola survivors, the virus can linger in the testes, central nervous system, and eyes long after it is gone from the rest of the body. "These are pressing questions," he says, and probably need to be addressed through tests around the treatment delivery method and timing. Those questions are hard to answer, though, because bringing patients back in for follow-up tests and sample collection is challenging in developing countries. "We'll probably have to rely more on animal data," he says.