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Two experimental treatments to treat Ebola infection work so well that they will now be offered to all patients in the Democratic Republic of Congo, scientists announced Monday.

The antibody-based treatments are so powerful — "Now we can say that 90% can come out of treatment cured," one scientist said — that they raise hopes that the disastrous epidemic in eastern Congo can soon be stopped.

Many families in the epidemic zone have been hiding their sick or bringing them in near death, too late to save. The epidemic has infected about 2,800 known patients and has killed more than 1,800 of them, according to the World Health Organization.

The treatments, known as REGN-EB3 and mAb-114, are both monoclonal antibodies that are infused intravenously into the blood and attach themselves to the outside of the virus, preventing it from invading the patient's cells.

The two treatments were part of a four-treatment trial that has been run with about 700 patients since November. They worked so well that a data-monitoring committee that met Friday immediately recommended that the other two treatments, ZMapp and remdesivir, be stopped and that all patients be offered REGN-EB3 and mAb-114.

Among patients who were brought into treatment centers with low viral loads — which suggested that they had been infected only days before — 6% of those who got REGN-EB3 died, and 11% of those who got mAb-114 died, according to Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases.

By contrast, 33% of those who received remdesivir, an antiviral drug, and 24% of those who got ZMapp, an older cocktail of monoclonal antibodies, died.

The difference in mortality rates between REGN-EB3 and mAb-114 was considered too small to be statistically significant, Fauci said.

It is helpful to have two options in case supply problems develop with one drug or the other, said Dr. Michael Ryan, director of emergency response for the World Health Organization.

The WHO and the NIAID made the announcement in conjunction with Dr. Jean-Paul Muyembe, director of Congo's National Institute for Biomedical Research.

The makers of the two treatments gave assurances that they could make enough doses to treat all patients, Fauci said.

Muyembe, 77, who has been fighting Ebola since it first appeared in 1976, pioneered the use of survivors' blood — which contains antibodies — in order to save patients. The two treatments that proved successful last week descend in part from his original research.

Asked how he felt about that during a telephone news conference, Muyembe said through a translator: "I'm a little sentimental. I had this idea a long time ago, and I've waited patiently for it. I'm very happy, and I can't believe it."

Fauci called him a "true hero."