At first, the program will make 500 million tests available, with a limit of four free tests for each residential address. They will ship within seven to 12 days of ordering, the White House said.

That could mean some Americans won’t start receiving their tests before the latest surge of Covid-19 has peaked in their area. Johns Hopkins University reported more than 527,000 new cases. The seven-day daily average is over 807,000, according to The Wall Street Journal’s analysis of Johns Hopkins data. Hospitalizations reached over156,000, a new high.

It also comes amid a national shortage of available tests. At-home kits started to fly off store shelves during the holidays as people rushed to test before gathering with friends and family, causing a national supply crunch.