The U.S. currently has capacity to run just 175,000 tests a week, according to an effort run by former FDA Commissioner Scott Gottlieb at the American Enterprise Institute. Even if those additional tests come online all at once, patients may not be able to get them. Right now, some health departments have not tested even patients with fevers and chest pain who are testing negative for other viruses. Efforts like drive-through testing centers, which were pioneered in South Korea and are now being launched by both New York state and developed by Trump administration in partnership with private industry, as announced today, could certainly help.

But every patient who has symptoms may need a test, and that will require even greater diagnostic capacity. Right now, the process is slow, with laboratories often taking several days to get back to doctors and patients. Thousands of tests came online this week from companies like Quest Diagnostics and LabCorp, but capacity has still lagged behind early promises — and the public health need.

The Roche case offers some encouragement: Brown said that the company started working on its new test last month, and finished the work in six weeks. Roche asked the FDA for emergency clearance earlier this week, and received it around the stroke of midnight Friday. As he announced a national emergency Friday afternoon, President Trump promised that testing capacity would eventually reach 5 million.