“We have to be really hard,” Michael Osterholm, the director of the Center of Infectious Disease Research and Policy and a member of Biden’s COVID-19 advisory board, said Thursday during an appearance on CNN’s New Day.

“I don’t care if I’m accused of being the Grinch that stole Christmas,” Osterholm added. “But you know what, I want you to be around for next Christmas and the Christmas after that. We should be having a very, very hard discussion right now about why we can’t have Christmas 2020 like we had in ‘19 or we hope to have in 2021.”

Coronavirus cases have been surging across the country in recent weeks. There are now more than 15 million diagnosed cases in the U.S. and 289,000 Americans have died, according to data from Johns Hopkins University.

The U.S. Centers for Disease Control and Prevention updated its holiday guidelines on Wednesday, saying that virtual celebrations or celebrating with members of your own household poses the lowest risk of spreading the virus. The center has also urged Americans not to travel for the winter holidays. If you do host a gathering with people from a different household, the CDC said to follow its advice on social distancing, holding events outside and wearing a mask when people are less than 6 feet apart or indoors.

Osterholm expressed some dissatisfaction with the CDC’s recommendations, telling CNN they were too “nuanced.”

“It’s basically saying don’t get together but if you are gonna get together do these things,” he said. “That’s like telling somebody don’t drive drunk but if you do drive drunk these are the best ways to do it.”

New Day host Alisyn Camerota then asked Osterholm to “give us that tough medicine” and explain his recommendations for the holiday season.

“At this point, no gatherings outside your immediate family that are in a sense podded together. And what I mean by that is the people who you have been with, who haven’t had outside exposures,” Osterholm said. He added that children who come home from college are not part of the household and either have to quarantine for 10 to 14 days or skip a holiday celebration.

“Don’t get together with neighbors. No Christmas parties,” Osterholm said. “There is not a safe Christmas party in this country right now unless everybody for the previous 10 to 14 days were podded.”

He added, “You know, I think many of my colleagues are saying limit it to 10 people, whatever. You know, that’s—that’s happy talk. We have to tell people what’s happening.”

The president-elect has repeatedly urged Americans to stay home this holiday season.

“This year, we’re asking Americans to forgo many of the traditions that have long made this holiday such a special one,” Biden said ahead of Thanksgiving. “For our family, we’ve had a 40-plus-year tradition of traveling over Thanksgiving, a tradition we’ve kept every year save one, the year after our son Beau died. But this year, we’ll be staying home.”

At a virtual event in Wilmington, Delaware earlier this month, Biden reiterated the need for people to stay home: “You cannot be traveling during these holidays as much as you want to.”

This story has been updated to include past statements from Joe Biden on staying home for the holidays.