Desperate Times: Public attention focused on untested drugs that might be used to treat Ebola after two Americans where given an experimental serum in August. The drug, called ZMapp, was given to Kent Brantly and Nancy Writebol after they stricken with the disease while working in Liberia.

Brantly and Writebol recovered, but health officials warned that the drug was only used because the benefits outweighed the risks. Because it hadn’t had the benefit of the years-long clinical trials required by the U.S. Food and Drug administration, there was no way to tell what the long-term health effects might be.

Health officials and drugmakers were working to fast-track treatment, but didn’t expect Phase I trials to be complete until January 2015. The drug given to Brantly and Writebol was only approved for emergency uses.

Critical Measures: Although several drugmakers where able to launch Ebola drug trials, a decline in the number of cases has brought at least one to a halt and threatens others.

The pharmaceutical company Chimerix announced that it would stop testing of its antiviral drug, brincidofovir, early this month, according to the New York Times. The trial, being held in Liberia, aimed at treating 140 patients but has seen less than 10 Ebola cases since its January 2 start date.

“The past weeks have brought the extremely positive news that Ebola infections are falling across West Africa, including in Liberia where our trial of brincidofovir was based,” University of Oxford professor Peter Horby, who led the trail, told The Guardian. “We’re delighted that infections are falling, but fewer patients makes it more difficult to carry out the robust scientific studies needed to ensure a new treatment will be safe and effective.”

Several other trials are facing similar circumstances, including a drug known as favipiravir, which is testing in Guinea and a trial testing plasma from the blood of Ebola survivors (known as convalescent serum). Both those trials are still ongoing, with the maker of favipiravir, called Avigan, stating that they had tested a “decent” number of patients and would attempt to find more, according to the Times. Last week, Guinea officials approved the drug for wider use, according to Reuters.

The Next Tests: Meanwhile, testing of ZMapp is about to move forward in Liberia, where the number of Ebola cases has once again ticked up, according to Scientific American. Guinea and Sierra Leone have opted not to participate based on the trial methodology, which uses a placebo control.

In addition to the fluctuating Ebola case count, it’s possible that Guinea’s approval of favipiravir could cause trouble for Zmapp and convalescent serum trials by muddying the factors used to interpret results. Widespread use would also make it more difficult to organize new trials, according to Scientific American.