Daily deaths from COVID have doubled since September, and the region could hit a total of 2.2 million virus deaths by March, according to the World Health Organization. The agency predicts that by that time, there will be “high or extreme stress in intensive care units” in 49 countries.

That is particularly concerning because Europe already has high vaccination rates compared to the rest of the world. Almost of two-thirds of Europeans has been fully vaccinated, the New York Times reported, compared to 59.2% of people in the U.S.

The fact that such a vaccinated population is still suffering a surge clearly shows “waning immunity,” Dr. Mark Dybul, CEO of Enochian BioSciences and a professor at Georgetown University Medical Center’s Department of Medicine, said at the Fortune CEO Initiative Conference. 

“What’s particularly disturbing about it is the hospitalization and death rates ticking up too,” said Dybul. “It’s equal among age groups. So this is different than what we’ve seen before.”

And this means that the same thing could happen as soon as a month from now in the U.S., Dybul predicted, though he added that the U.S. is further along with booster shots than Europe.

Although America might follow Europe’s infection trajectory, and Thanksgiving celebrations could increase that likelihood, we might not respond to an uptick in cases the same way.

On Monday, Austria began a nationwide lockdown to combat Europe’s “fourth wave” of the virus, after becoming the first Western nation to mandate COVID-19 vaccinations for everyone starting February 1. Bloomberg reports that Belgium has asked its population to work from home four days per week until the middle of December, and Ireland has been asked to consider the same, although a full lockdown doesn’t seem likely, according to TheJournail.ie.

That is unlikely to happen in the U.S. 

“We can curb the spread of the virus without having to in any way shut down our economy,” White House Covid-19 coordinator Jeff Zients said on Monday. The Centers for Disease Control and Prevention and the State Department recommend that Americans “avoid travel” in Western Europe as their surge heats up.

He added that 82% of the US adults have received at least one shot.