Dr Bruce Aylward, senior advisor to the WHO Director-General, also defended the U.N. agency's relationship with China, saying its work with Beijing authorities was important to understand the outbreak which began in Wuhan.
"It was absolutely critical in the early part of this outbreak to have full access to everything possible, to get on the ground and work with the Chinese to understand this," he told reporters.
"This is what we did with every other hard hit country like Spain and had nothing to do with China specifically."
He also defended WHO recommendations to keep borders open, saying that China had worked very hard to identify and detect early cases and their contacts and ensure they did not travel in order to contain the outbreak.
On Europe, Kluge described the outbreak of coronavirus there as "very concerning" and urged governments to give "very careful consideration" before relaxing measures to control its spread.
"A dramatic rise in cases across the Atlantic skews what remains a very concerning picture in Europe," he said. "We still have a long way to go in the marathon."