"But the go-ahead never came"

On March 21 — when the U.S. had recorded only a few hundred COVID-19 deaths — Bosch submitted the test for emergency authorization, a process the Food and Drug Administration uses to expedite tests and treatments.

A green light from the FDA could have made a big difference for the many Americans who were then frantically trying to find doctors to swab their noses, with results, if they were lucky, coming back only days later.

But the go-ahead never came.

In the months that followed, Bosch responded to repeated requests from FDA reviewers for data and studies. When the agency finally put out guidance that summer about the performance over-the-counter home tests needed to meet, officials required that such tests be nearly as sensitive as the lab tests used to definitively determine whether a patient has COVID-19.

That standard proved difficult to meet. Rapid tests are usually sensitive enough to detect viral antigens when someone has enough of them to be able to spread the disease. Such tests are not as good at picking up cases in either earlier or later stages of infection, when viral loads are lower.