Dr. Bruce Aylward shows graphics related to the coronavirus during a press conference at the WHO headquarters in Geneva on Tuesday, February 25. Fabrice Coffrini/AFP/Getty Images

Dr. Bruce Aylward, team lead for the World Health Organization-China joint mission on coronavirus, addressed the possibility that the virus could become a pandemic at a news conference today.

“Folks, this is a rapidly escalating epidemic in different places that we’ve got to tackle super-fast to prevent a pandemic.”

Aylward and a team of 25 people visited several areas in China, including Wuhan, to see how China was addressing the virus. Aylward said China is using basic public health tools and applying them with rigor and innovation on a scale never seen in history.

“It’s the unanimous assessment of the team that they have changed the course of this outbreak. What was a rapidly escalating outbreak has plateaued and then come down faster than one would have expected,” Aylward said, adding hundreds of thousands of people in China did not get this because of this response.

What is a pandemic? A disease outbreak is the occurrence of disease cases in excess of what's normally expected, according to WHO. An epidemic is more than a normal number cases of an illness, specific health-related behavior or other health-related events in a community or region.

A pandemic is defined as the "worldwide spread" of a new disease. The last pandemic reported was the H1N1 flu pandemic in 2009, which killed hundreds of thousand worldwide.

Although WHO has declared the outbreak a "public health emergency of international concern," the outbreak has not met the criteria needed to be described as a pandemic when it comes to its geographical spread and impact, WHO Director-General Tedros Adhanom Ghebreyesus said during Monday.