President Barack Obama said he was considering appointing an Ebola "czar" to coordinate the fight against the virus in the United States, but he remained opposed to a ban on travel from West Africa.
Mr. Obama authorised calling up military reservists for the U.S. fight against Ebola in West Africa on Thursday.
U.S. concerns have intensified after two Texas nurses who cared for a dying Liberian patient contracted the virus that has killed nearly 4,500 people. The disease continues to spread in West Africa where the outbreak began in March, and reached the last remaining district in Sierra Leone that had not been affected by Ebola.
U.S. lawmakers held a congressional hearing about the administration's handling of the Ebola outbreak in the United States. Some have called for a czar and a ban on travel from West Africa.
"It may be appropriate for me to appoint an additional person" to oversee efforts to contain Ebola, Mr. Obama told reporters after meeting aides involved in the fight against the disease.
He said he had no philosophical objection to a travel ban but that some travellers might attempt to enter the United States by avoiding screening measures, which could lead to more Ebola cases, not fewer.
U.S. Federal Aviation Administration chief Michael Huerta told reporters separately that the government was assessing whether to issue a travel ban "on a day-to-day basis."
Schools close in Texas, Ohio
Amber Vinson, one of the nurses, who treated the Ebola patient at Texas Health Presbyterian Hospital in Dallas and contracted the virus, travelled to Ohio over the weekend on a Frontier Airlines flight while running a slight fever.
Dr. Christopher Braden, a spokesman for the Centers for Disease Control and Prevention (CDC), said Ms. Vinson may have been ill as early as Friday, when she boarded the flight from Dallas to Cleveland. Vinson returned to Texas on Monday.
Dr. Thomas Frieden, the CDC director, said it is unlikely passengers who flew with Ms. Vinson were infected because the nurse had not vomited or bled on the flight, but he said she should not have boarded the plane.
Concerns about Ebola exposure prompted several schools in Ohio and Texas to close because people with ties to the schools may have shared the flight with Ms. Vinson.
An air ambulance transported Vinson to Atlanta's Emory University Hospital on Wednesday for treatment. The first nurse to contract Ebola, Nina Pham, 26, was flown to the National Institutes of Health (NIH) in Bethesda, Maryland, to be treated in an isolation unit.
A YouTube video made by Ms. Pham's physician, Dr. Gary Weinstein, before her discharge showed her in a bed at Texas Health Presbyterian Hospital and with Dr. Weinstein in protective gear.
In the video, Ms. Pham wiped away tears and said, "Come to Maryland, everybody!" and "I love you guys." She requested that the video be shared by the hospital.
