Pauline Cafferkey, the British nurse being treated for Ebola, is receiving an experimental drug and blood from Ebola survivors. The hospital said she was as well as can be hoped, but the coming days are critical. CCTV America’s Richard Bestic reported this story from London.

Cafferkey is receiving treatment confined to a quarantine tent, preventing any contact with family or medical staff.

Michael Jacobs, a physician at the Royal Free Hospital who is leading her treatment said much of it was experimental.

“We’ve decided to treat her with two things. The first of which is convalescent plasma, and that means a product taken from the blood of another patient who has recovered from Ebola. That product contains antibodies which we hope will help her fight the infection,” Jacobs said. “The second thing that we’ve given her is an antiviral drug. It’s an experimental antiviral drug. She’s very well aware that this is experimental treatment that is not proven to work. You’re probably all aware that there is no specific treatment for Ebola that has been proven to work, and so we’re just making choices from the available options that we have, in concert with Pauline who is helping us make these choices.”

The questions surrounding Cafferkey’s treatment mirrored wider concern over the failure of the U.K.’s screening of volunteer health workers returning from battling Ebola in West Africa.

Cafferkey had been tested twice, once departing Sierra Leone and once on arrival.

Britain’s Chief Medical Officer is undertaking a review of procedures.

“What has become clear to me is that the process was not as it should have been. There were queues. We knew 37 healthcare workers were coming in together. We did not have enough staff there from Public Health England . So we need to sort that out, and they need to make sure that when we next have a group coming in. We have sufficient people there,” Sally Davies, U.K. chief medical officer said.

Around 200 people in Britain have been assessed or tested for Ebola in recent months. Cafferkey is the first to be diagnosed with the virus on British soil.