A top envoy of the World Health Organization warned Sunday that the coronavirus will be a "virus that stalks the human race for quite a long time" until a vaccine is developed.

Dr. David Nabarro, a special envoy of the WHO, said there are signs that the rate of new infections could be starting to slow in the U.S. and Europe thanks in part to "very rapid" mitigation, NBC News reports.

But he added that the virus is still "advancing in other parts of world" and that communities around the globe will need to develop an infrastructure and capacity to defend against sporadic outbreaks in the coming months before lifting restrictions and trying to return life to a sense of normalcy.

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"We are not so sure it will come in waves in the way that influenza does. We think it's going to be a virus that stalks the human race for a quite a long time to come, until we can all have a vaccine that will protect us," he said.

"The key for this particular virus is that every community has a kind of defensive shield, can pick up cases as soon as they appear, isolate them and stop outbreaks from developing. It's going to be necessary for every single country to have that capacity."

There were more than 1.8 million confirmed cases of COVID-19 in the world by Sunday night, according to Johns Hopkins University's Coronavirus Resource Center.