"She has not been reinfected with the Ebola virus. She has become unwell due to meningitis caused by the Ebola virus.
"In the last few days she has seen a significant improvement. She is still in bed all the time but she is able to talk. She has got a long recovery ahead of her."
He continued: "We do not use term 'critically ill' lightly. Pauline developed neurological complications due to meningitis brought on by Ebola.
"We are very hopeful that [she] will make a full recovery."
Dr Jacobs went on to describe her illness as an "unprecedented situation" as he revealed she is being treated with an experimental drug.
Cafferkey, from South Lanarkshire, Scotland, first contracted the Ebola virus while working in Sierra Leone in December 2014. She spent several weeks in an isolation unit at the hospital at the start of this year and was released on January 24.
She was re-admitted to hospital in October this year and was said to be critically ill. She is the first person to have been diagnosed with Ebola on British soil.
