Last week, two American patients who reportedly received a dose of an experimental drug to treat the Ebola virus, which has not yet approved for human use, and had different reactions. One of them had the symptoms of the virus almost completely disappear … and quickly, according to a source speaking with CNN.

Dr. Kent Brantly cares for an Ebola patient in the isolation ward before he tested positive for the virus. (Image source: Samaritan's Purse)

Dr. Kent Brantly cares for an Ebola patient in the isolation ward before he tested positive for the virus. (Image source: Samaritan’s Purse)

The Ebola virus outbreak in West Africa is the largest in recorded history. Of the more than 1,300 people infected as of Monday, one was Dr. Kent Brantly, who was brought back to the United States Saturday, and another was Nancy Writebol, who is supposed to arrive in the U.S. Tuesday. Both were from North Carolina and worked for the same mission Samaritan’s Purse.

With the mission, Brantly, as a doctor, treated Ebola victims near Monrovia, Liberia, while Writebol worked as a hygienist whose role included decontaminating those entering or leaving the Ebola treatment area at that hospital.

After it was confirmed they both had the virus, a “secret serum” reportedly made by Mapp Biopharmaceutical Inc. was shipped to them in Liberia under strict instructions as for how it was to be cared for and administered, according to a source speaking with CNN.

Frozen vials of the treatment arrived Thursday, according to CNN, and were to thaw naturally for up to 10 hours. While Brantly wanted Writebol to receive the first dose, after he took a turn for the worse, a source told CNN, he asked for it. Within an hour after the medication was administered to him intravenously, the source said Brantly experienced a reversal of the symptoms. CNN reported one of the doctors calling it “miraculous.”

Writebol’s first dose, on the other hand, was not as successful, but her second dose resulted in some improvement.

A picture taken on July 24, 2014 shows staff of the Christian charity Samaritan's Purse putting on protective gear in the ELWA hospital in the Liberian capital Monrovia. An American doctor battling West Africa's Ebola epidemic has himself fallen sick with the disease in Liberia, Samaritan's Purse said on July 27. (AFP/ZOOM DOSSO ZOOM DOSSO/AFP/Getty Images)

A picture taken on July 24, 2014 shows staff of the Christian charity Samaritan’s Purse putting on protective gear in the ELWA hospital in the Liberian capital Monrovia. An American doctor battling West Africa’s Ebola epidemic has himself fallen sick with the disease in Liberia, Samaritan’s Purse said on July 27. (AFP/ZOOM DOSSO ZOOM DOSSO/AFP/Getty Images)

Within the last couple of years, the Mapp drug showed promising results in preventing the disease in nonhuman primates. According to a news release, all the monkeys survived if they were injected with the “cocktail of monoclonal antibodies” an hour after infection. Two-thirds were protected if it was administered within two days of infection.

Later research showed that the drug was effective even after symptoms appeared as well.

But if the drug isn’t allowed yet for human use, how did these two Americans get it? CNN pointed to the Food and Drug Administration’s “compassionate use” rule.

This rule allows the use of an “investigational drug outside of a clinical trial to treat a patient with a serious or immediately life-threatening disease or condition who has no comparable or satisfactory alternative treatment options.” There is no vaccine or antidote for the Ebola virus yet.

The use of such drugs under this regulation, according to the FDA, is on a case-by-case basis. The FDA also warns of the potential for serious side effects from drugs that have not yet been through human trials.

Watch CNN’s medical correspondent talk about the use of this experimental drug on these two patients:

Dr. Anthony Fauci of the National Institutes of Health said Monday an Ebola vaccine is not far from coming to the market. He told ”CBS This Morning” it has already successfully tested with monkeys and will begin human trials with volunteers in September. He expects that a finalized version of the vaccine could be available by next July.

Mapp Biolopharmaceutical did not immediately return TheBlaze’s request for comment on whether its drug is the vaccine that Fauci referenced or if it was the one sent to help the two American patients with the virus.

More than 1,300 people have been stricken in West Africa, and nearly 730 have died in Guinea, Liberia and Sierre Leone. On Monday, Nigeria reported seeing its second case of Ebola.

The Associated Press contributed to this report.

We will be discussing this story and all the day’s news on our live BlazeCast with Editor-in-Chief Scott Baker (@bakerlink):

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