Two of the four drugs used since November in a broad clinical trial to treat Ebola patients in the Democratic Republic of the Congo have shown promising results.
Between 70 and 90 percent of patients survive with both drugs – the highest proportion is found among those with the lowest virus levels in the blood. Of those who received two other drugs, 50-75 percent survive.
Up to two-thirds of those infected with Ebola die without treatment.
“This is fantastic news. It gives us new tools in the Ebola toolkit, even if they themselves don't stop Ebola, says Mike Ryan, director of the World Health Organization's emergency program.
Both promising preparations mAb114 and REGN-EB3 are developed from antibodies taken from people who have experienced Ebola.
According to the US NIAID health agency, which funded the study, 71 percent of those who received REGN-EB3 and 66 percent of those who received mAb114 survived, Reuters reported.
Among patients with low virus levels, the survival rates are 94 and 89 percent, respectively.
All four drugs began to be used last November in the Congolese Ebola epidemic as part of the first randomized multi-drug trial of the WHO.
On Monday, the WHO and its partners decided to abandon the other two drugs, resulting in worse results.
The decision is based on an analysis of 499 treated patients. The aim of the study is to treat 725 patients, but last Friday the independent monitoring body DSMB recommended ending the study with four drugs and treating all patients now with only mAb114 and REGN-EB3.
So far, 681 patients have been treated with four drugs in four clinics in the Eastern Democratic Republic of the Congo.
Reliable results have also been welcomed by Jeremy Farrar, Head of Wellcome Trust, a British aid organization.
"We will never get rid of Ebola, but we must be able to prevent outbreaks in major national and regional epidemics," Farrar said in a statement.
An Ebola outbreak in eastern Congo that started a year ago, this is the second deadliest so far. At least 1,800 people have died. The fight against the disease is hampered by poor infrastructure and violence by local militias.
Ebola outbreak in West Africa in 2013 to 2016 requires just over 11,000 deaths.