Tedros Adhanom Ghebreyesus, director general of the World Health Organization (WHO), speaks during a news conference on the COVID-19 coronavirus outbreak in Geneva, Switzerland, on Monday, March 2, 2020.

World Health Organization officials are "deeply concerned" about the "rapid escalation and global spread" of the coronavirus outbreak, saying global infections will eclipse 1 million with 50,000 deaths in a few days.

"Over the past five weeks, we have witnessed a near exponential growth in the number of new cases, reaching almost every country, territory and area," WHO Director-General Tedros Adhanom Ghebreyesus said at a news briefing at the organization's Geneva headquarters Wednesday.

The world knew almost nothing about the virus three months ago, when reports of a novel coronavirus first started surfacing in Wuhan, China. Tedros emphasized how much scientists still don't know about the virus, saying this is the world's first pandemic caused by a coronavirus "and whose behavior is not really known." Scientists have traced the coronavirus back to bat DNA, saying it likely jumped from there to a pangolin before jumping to humans.

The last time the WHO declared a pandemic was during the 2009 H1N1 swine flu outbreak. The 2002-2003 outbreak of SARS, which is also a coronavirus, was contained enough to avoid that classification.

"COVID-19 is a real threat. It is a real threat to everyone on the planet," said Dr. Maria Van Kerkhove, the WHO's technical lead on the outbreak.

On Monday, WHO officials said government lockdowns aren't enough to contain the coronavirus outbreak. However, they are necessary, despite their impact on the economy and society, they said. Without them, the coronavirus would kill even more people.

"This is serious. This is a deadly virus, people will get through it, countries will get through it," said Dr. Mike Ryan, executive director of the WHO's health emergencies program.

World leaders need to build out their public health systems "if we're going to get out of an interminable cycle of economically punishing lockdowns and shutdowns," Ryan said. "We must get back to be able to control this virus, live with this virus, develop the vaccines that we need to finally eradicate this virus."

Ryan said that it's too early for anyone to determine the impact of shutdown or lockdown measures on disease transmission at this point. Each country should focus on adapting consistent policies and adapting their strategies against the disease, and then measuring how effective they were in suppressing infection. "I'd love to say there's an easy way to do this, I'd love to say that there's way out of this without that kind of hard work, but there isn't." Ryan said.

Globally, the coronavirus has infected more than 885,000 people and has killed at least 44,000, according to Johns Hopkins University data.