GENEVA, Feb. 28 (Xinhua) -- A senior World Health Organization (WHO) expert said here Friday that it is unhelpful to declare a pandemic when people are still trying to contain COVID-19, although the WHO has raised the epidemic risk alert to the highest level.

The WHO revised Friday the risk assessment of COVID-19 from "high" to "very high" at global level, as an increasing number of cases in more countries were reported over the last few days.

"A Pandemic is a unique situation, in which all citizens on the planet will likely be exposed to a virus within a defined period of time," Michael Ryan, executive director of WHO Health Emergencies Program, said at a daily briefing.

However, in the case of COVID-19, it has been proved that the course of the epidemic can be significantly altered through containment measures and robust public health response, the expert noted.

The word "pandemic" is "colloquial," Ryan said, appealing for actions that go beyond colloquial terms.

The existing data do not support the concept of a pandemic so far, he said, highlighting that China has clearly shown that it is not necessarily the natural outcome of COVID-19 epidemic if indispensable responses are made quickly.