Ideally, we would test everyone in the country with symptoms of COVID-19, every one of their contacts, every hospitalized patient, and many people in places such as nursing homes, homeless shelters, prisons, and jails where the virus can spread explosively and kill quickly. That would be over a million tests a day, more than four times more than we are doing now. And that's without even considering testing others at risk, such as health care and other essential workers who don't have symptoms. That would require millions of more tests per day.