Insurers say they were blindsided when the Biden administration announced Thursday that private insurance plans will be required to cover at-home COVID-19 tests purchased over-the-counter, and they have lots of questions, including whether Medicaid and Medicare plans also must cover the OTC tests, whether there will be guardrails against fraud and abuse, and how the government will ensure test prices are kept in check. A source has heard from one plan that believes if just 5% of enrollees submit testing...