The government promised to step up its response to the Ebola crisis after federal officials acknowledged that a second nurse infected with the virus was cleared to fly a day before her diagnosis.

Dr. Tom Frieden, director of the Centers for Disease Control and Prevention (CDC), had originally told reporters on Wednesday that the nurse from Dallas, Amber Joy Vinson, “should not have traveled on a commercial aircraft” because she had been exposed to the virus while caring for Thomas Eric Duncan, an Ebola patient who traveled to the U.S. from Liberia.

But a CDC spokesman later told NBC News that Vinson had contacted the CDC before getting on her flight because she had a slight fever and that she “was not told that she could not fly.”

A CDC official cleared Vinson to board the Frontier Airlines flight from Cleveland to the Dallas area. Her reported temperature — 99.5 degrees — was below the threshold set by the agency and she had no symptoms, according to agency spokesman David Daigle.

Vinson was being monitored more closely since another nurse, Nina Pham, also involved in Duncan’s care was diagnosed with Ebola. Duncan, who traveled to the U.S. from Liberia, originally was sent home when he went to the Dallas hospital’s emergency room, only to return much sicker two days later. He died of Ebola on Oct. 8.

In a written testimony dating Wednesday, Oct. 16, Chief Clinical Officer and Senior Executive Vice President for Texas Health Resources Daniel Varga said the hospital in which Duncan was treated was “deeply sorry” for the blunders they’ve made while handling the case.

Medical records provided to The Associated Press by Duncan’s family showed Vinson inserted catheters, drew blood and dealt with Duncan’s body fluids. Late Wednesday, she arrived in Atlanta to be treated at Emory University Hospital, which has already treated three Americans diagnosed with the virus.

“Unfortunately, in our initial treatment of Mr. Duncan, despite our best intentions and a highly skilled medical team, we made mistakes. We did not correctly diagnose his symptoms as those of Ebola,” he wrote.

CDC working closely w/Texas hospital & staff around the clock. Intensive efforts underway to train & retrain staff on #Ebola preparedness.

— Dr. Tom Frieden (@DrFriedenCDC) October 15, 2014

More than 70 other health care workers involved in Duncan’s care were being monitored.

While Ebola patients are not considered contagious until they have symptoms and only two persons have been known to contract the disease in the U.S., the revelations on Wednesday raised new alarms about whether hospitals and the public health system are equipped to handle the deadly disease.

Frieden, the head of the CDC, previously said that there had been some sort of “breach of protocol” when Pham, the first nurse contracted virus. He later apologized for suggesting that the nurse was somehow responsible for causing her own infection.

On Tuesday, he also acknowledged CDC should have sent “a more robust hospital infection control team” after the first case of Ebola was discovered in Dallas.

Federal health officials are being called to testify before a congressional committee Thursday to explain where things went wrong.

House Panel Hearing To Examine Public Health Response To Ebola Outbreak http://t.co/UVIxGD97oP

— NPR Health News (@NPRHealth) October 16, 2014

President Barack Obama directed his administration to respond in a “much more aggressive way” to oversee the Dallas cases and ensure the lessons learned there are transmitted to hospitals and clinics across the country. For the second day in a row he canceled out-of-town trips to stay in Washington and monitor the Ebola response.

Ebola is a deadly disease that spreads through contact with a symptomatic person’s bodily fluids, including blood, sweat, vomit, feces, urine, saliva or semen. More than 4,400 people have died in the ongoing epidemic, centered in West Africa.

Vinson was diagnosed with Ebola a day after the flight, news that sent airline stocks falling amid fears it could dissuade people from flying. Losses between percent 5 and 8 percent were recorded before shares recovered in afternoon trading.

Frontier has taken the aircraft out of service. The plane was flown Wednesday without passengers from Cleveland to Denver, where the airline said it will undergo a fourth cleaning, including replacement of seat covers, carpeting and air filters.

The Associated Press contributed reporting.

Have something to add to this story? Share it in the comments.