The US experts have been sidelined for weeks, ordered away from the region because of State Department security concerns.
New statements in two top medical journals this week are calling on the U.S.to change its mind and send its experts back where they are sorely needed.
In October, WHO convened a meeting of worldwide organisations, United Nations partners, countries at risk of Ebola, drug manufacturers and others to agree on a framework to continue trials in the next Ebola outbreak, whenever and wherever it occurs. Many new cases have been unrelated to known infections, alarming evidence that gaps in tracking the disease remain.
The world's worst outbreak, which lasted from 2014 to 2016, killed more than 11,000 people in Liberia, Guinea and Sierra Leone.
"There have been 241 deaths", the ministry said in an update correct to November 26, indicating there had been a total of 421 cases - 374 of them confirmed, and another 47 probable.
"It is in US national interests to control outbreaks before they escalate into a crisis", one group of global health experts wrote in a commentary in the Journal of the American Medical Association.More news: Trump warns US may cut off General Motors subsidies after job cuts
'Those facilities, we believe, are one of the major drivers of transmission, ' said Peter Salama, the WHO's emergency response chief. Many venture out on critical virus containment missions only accompanied by United Nations peacekeepers in areas where gunfire echoes daily.
He added that it was "highly likely" that the outbreak would not be under control for another six months. The conflict slows healthcare workers' attempts to fight the virus. The trial is the first-ever multi drug trial for treatment of Ebola.
Speaking to The Associated Press on Friday from the outbreak zone, the Ebola response program director for the International Rescue Committee, Dr. Stacey Mearns, said the absence of the CDC's experts can be felt acutely.
The trial aims to determine which of the four leading Ebola treatments - referred to by the World Health Organization as mAb114, Regeneron, Remdesivir and ZMapp - proves most successful in combating a virus that can have a high fatality rate.
In a situation report released Wednesday, WHO said it is "confident that the outbreak can be contained despite ongoing challenges".
The WHO said that although the risk of a global spread remains low, the risk of the outbreak spreading to other provinces in the Democratic Republic of the Congo as well as to neighboring countries remains "very high".