Every American Should Be Tested for Covid-19 Once a Week

Americans are still doing Covid-19 testing wrong. The kind of testing and contact tracing that scientists advocated in the spring to combat the virus isn’t working in the U.S. And it won’t be improved by the new $50 at-home test made by startup Lucira Health Inc., which was just given emergency authorization this week by the Food and Drug Administration.

That’s because a biological quirk of this disease means the current testing system misses the bulk of the cases in their most contagious period. But a different strategy would catch them. And we already have the technology to do it.