Spanish nurse Teresa Romero, 44, appeared to be recovering from Ebola Saturday after reportedly receiving the experimental treatment ZMapp. Romero, who is the only known person to have contracted the deadly virus outside Africa, was conscious and sitting upright without assistance Saturday, Reuters reported.

The crisis, however, is far from over. Though Romero appears to be improving, she has not yet beaten the disease, and there are now 16 people in Madrid hospitals under observation for signs of having contracted the Ebola virus, the Associated Press reported Saturday.

"Teresa Romero's condition has undergone no significant changes and is still serious, but stable," an Ebola committee set up by the Spanish government said in a Saturday statement obtained by Reuters.

Romero received a dose of ZMapp Friday, the New York Daily News reported, quoting "health sources." The experimental treatment, of which health officials have said there were very few if any doses left, appears to have helped boost her recovery. ZMapp was widely seen as instrumental in saving the lives of two American aid workers who contracted Ebola in West Africa earlier this summer and beat the disease at an Atlanta hospital.

The Romero case has had a major psychological impact on the people of Spain, and even health care workers at Madrid's Carlos III hospital -- which is currently treating Romero -- have been spooked by the Ebola scare, with some refusing to help Ebola victims. Four health workers are in quarantine at the facility on suspicion of having Ebola, the Guardian reported. Romero contracted the virus while helping two priests who contracted the disease while in West Africa and was diagnosed Oct. 6.

Spanish Prime Minister Mariano Rajoy visited the hospital Friday to announce a commission would investigate how to keep Ebola from spreading across the country.

The current Ebola outbreak, officially the worst in history, has officially killed more than 4,000 people in seven countries, health authorities announced earlier this week. The United Nations has estimated that it could cost nearly $1 billion to bring an end to the epidemic.