The World Health Organization warned on Thursday that there’s no returning to the “old normal” as new coronavirus cases continue to accelerate in the U.S. and other parts of the world.

“It’s completely understandable that people want to get on with their lives, but we will not be going back to the old normal,” WHO Director-General Tedros Adhanom Ghebreyesus said during a news conference from the agency’s Geneva headquarters.

WHO data shows that half of all coronavirus cases reported so far are from three countries: the U.S., Brazil and India.

With nearly 4 million confirmed cases, the U.S. has, by far, the worst outbreak in the world. Brazil follows with 2.2 million cases and India 1.2 million.

There are now more than 15.3 million confirmed cases of coronavirus worldwide, including at least 625,000 deaths, according to the latest data from Johns Hopkins University.

Tedros urged world leaders and the general public to make “good choices” in battling this ongoing pandemic.

“Just because cases may be at a low level where you live, that doesn’t make it safe to lower your guard,” he said.

“Don’t expect someone else to keep you safe. We all have a part to play in protecting ourselves and one another.”

In echoing those sentiments, President Donald Trump this week warned that the coronavirus pandemic in the U.S. will probably “get worse before it gets better.”

After months of resisting to wear a face mask or covering in public and questioning its effectiveness, he said that it is now a “patriotic” action to take during this health crisis.

The WHO and medical experts have noted that the virus can spread through respiratory droplets that pass when an infected person coughs or sneezes. Recent studies have suggested that not wearing a face mask dramatically increases a person’s chance of being infected by the coronavirus.

Other experts have asserted that the coronavirus could spread through aerosolized droplets, particularly in poorly ventilated spaces.

The CDC also released a new study that said state leaders should strongly consider requiring face masks and coverings to curb the spread of the virus.

White House coronavirus advisor Dr. Anthony Fauci, the nation’s top infectious disease expert, said this week that it is unlikely that the coronavirus will ever be eradicated.

Ethen Kim Lieser is a Minneapolis-based Science and Tech Editor who has held posts at Google, The Korea Herald, Lincoln Journal Star, AsianWeek and Arirang TV. Follow or contact him on LinkedIn.