Liberia and Guinea have met a Dec. 1 target for isolating 70 percent of people infected with Ebola and safely burying 70 percent of those who die but Sierra Leone has not, the World Health Organization said Monday.

Only last week, the U.N. health agency said only Guinea was on track to meet the targets for getting the Ebola outbreak under control in the three hardest-hit West African countries.

But at a news conference in Geneva, WHO's Dr. Bruce Aylward said the organization had revised its conclusion based on more analysis of its data. Sierra Leone also probably met the targets in the west of the country, he said, and likely will improve to the 70 percent target nationwide "in the coming weeks."

Aylward also told reporters that WHO's ambitious plan to stop the deadly Ebola outbreak in West Africa has shown it is possible to quickly reduce the "yawning gap" between disease levels and the capacity to respond.

"You can catch up with Ebola even on this scale," he said.

WHO launched its Ebola its 70 percent plan two months ago.

In Freetown, Sierra Leone, on Monday, the chief executive of the National Ebola Response Centre, retired Maj. Alfred Palo Conteh, acknowledged that "as far as meeting the 70 percent isolation target, we did not do well and could have done better."

He said authorities there need more beds for isolation, adding that 400 beds are expected in the next two weeks.

U.N. Ebola chief David Nabarro, speaking to reporters in Freetown, said, "the intensity of the Ebola transmission in some parts of Sierra Leone is very high and the situation is getting serious each day, and could worsen."

Over the last two months, "tremendous progress" has been made in containing the spread of the disease, he said, and the next 60 days will be crucial - "it is left with the Sierra Leoneans themselves to make the difference."