A new study estimates that more than five million American workers lost their insurance this spring, a number higher than those in any full year of insurance losses. Four of every five people who have lost employer-provided health insurance during the coronavirus pandemic are eligible for free coverage through expanded Medicaid programs or government-subsidized private insurance through the Obama-era health law, according to the Kaiser Family Foundation. But experts say that insuring the recently unemployed is a difficult challenge. Many people cannot afford premiums for coverage through either the health care law or the program known as COBRA, for the Consolidated Omnibus Budget Reconciliation Act. Others might not know they are eligible for Medicaid.