Americans keep hearing that it is important to test frequently for covid-19 at home. But just try to find an “at-home” rapid covid test in a store and at a price that makes frequent tests affordable. Testing, as well as mask-wearing, is an important measure if the country ever hopes to beat covid, restore normal routines and get the economy running efficiently. To get Americans cheaper tests, the federal government now plans to have insurance companies pay for them. The Biden administration announced Jan. 10 that every person with private insurance can get full coverage for eight rapid tests a...