US President Barack Obama (R) tours the Vaccine Research Center with Dr. Nancy Sullivan (L), U.S. Secretary of HHS Sylvia Burwell (2nd L), and Dr. Anthony Fauci (2nd R) to talk about Ebola, during a visit to the National Institutes of Health in Bethesda, Maryland December 2, 2014. [Photo/Agencies]

BETHESDA - US President Barack Obama heralded strides in the effort to confront Ebola in West Africa and in protecting the US against the spread of the deadly virus. He said squelching the disease remains an urgent priority even if the American public's attention has shifted elsewhere.

"We cannot let down our guard, even for minute," Obama said. "We can't just fight this epidemic, we have to extinguish it."

Obama spoke Tuesday after touring the National Institutes of Health in Washington's Maryland suburbs where he witnessed advances in Ebola-fighting research. He highlighted the NIH's progress in developing an Ebola vaccine, calling the initial results "exciting" while cautioning that there are "no guarantees" about the vaccine's ultimate success.

NIH researchers last week reported that the first safety study of a vaccine candidate found no serious side effects, and that it triggered signs of immune protection in 20 volunteers. US health officials are planning much larger studies in West Africa to try to determine if the shots really work.

"No potential Ebola vaccine has ever made it this far," Obama said.

He prodded Congress to approve his request for $6.2 billion in emergency spending against the outbreak, urging lawmakers to act before they break for the holidays.

"We can't beat Ebola without more funding," he said. "It's a good Christmas present to the American people and to the world."

The public attention to Ebola by the president comes as Congress is assembling a massive spending bill to keep the government operating. But the legislation has become entangled with Obama's executive actions on immigration, which Republicans want to block.

Any final spending bill is expected to contain a pared down version of Obama's Ebola request. Obama asked for $2 billion for the United States Agency for International Development, $2.4 billion for the Department of Health and Human Services, and more than $1.5 billion for a contingency fund, the first item that lawmakers would likely trim.

The White House said Tuesday that Ebola Response Coordinator Ron Klain, in an update to Obama, reported that the US is better prepared to deal with Ebola at home and that administration efforts to confront the virus in Liberia, Guinea and Sierra Leone are further along than two months ago.