With schools set to reopen soon and debate continuing about whether there should be in-person classrooms, it still remains an "open question" how much children under the age of 10 are able to spread coronavirus, Dr. Deborah Birx, the coordinator of the White House Coronavirus Task Force, said Friday. 

"I think that is still an open question that needs to be studied in the United States," Birx said on NBC's "Today." "We certainly know from other studies that children under 10 do get infected, it's just unclear how rapidly they spread the virus."

Birx told show anchor Savannah Guthrie that it is known that children under the age of 18 usually don't suffer severe forms of COVID-19, but there are still some who have "terrible consequences if they have underlying conditions. What I can't tell you for sure despite the South Korea study is whether children under 10 in the United States don't spread the virus the same as children over 10."

In the South Korea study, it was determined that children younger than 10 transmit COVID-19 less than adults do, but they can still spread it, and children between the ages of 10 and 19 can spread it just as much as adults can. 

Birx told Guthrie that school districts should follow the Centers for Disease Control and Prevention guidelines on reopening, which "really give parents, school administrators, teachers, and the county supervisors really an understanding of where they are in the epidemic and what precautions they need to take."

She also stressed the importance of wearing masks, social distancing, and washing hands to slow the spread of coronavirus. 

Meanwhile, with the numbers now passing 4 million nationwide, "we have to change our behavior now before this virus completely moves back up through the north."

She said there are some signs that the disease rates may be starting to plateau in Texas, California, Arizona, and Florida, but it "depends on the next set of cities" about how much worse the pandemic's effects in the United States can be. 

“And so we’re really having to respond as an American people, and that’s why you hear us calling for masks and increased social distancing to really stop the spread of this epidemic,” Birx said. "It's very serious, and it's very real ... we all need to protect those who need our protection right now."

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