Centers for Disease Control and Prevention (CDC) Director Robert Redfield told Congress on Thursday that the country needs between 30,000 and 100,000 people working on contact tracing in order to help contain the next wave of the coronavirus.

The estimate shows the daunting challenge of hiring an army of people to interview those infected with coronavirus to identify who they have been in contact with so that those people can quarantine and help prevent the spread of the virus.

“I’ve estimated between 30 and 100,000” contact tracers are needed,” Redfield told the House Appropriations Committee during a hearing Thursday. He acknowledged the figure is “sizable,” though it is actually less than the 300,000 people former CDC director Tom Frieden has estimated the U.S. will need.

Read more at The Hill.