To gauge how much the federal government’s COVID assistance helped the nation’s disadvantaged children, consider what happened after the relief stopped. Millions of low-income children have lost their health insurance and the COVID tax relief that had lifted their families out of poverty. In March 2020, President Trump signed the Families First Coronavirus Response Act, which, among other provisions, barred state Medicaid programs from dropping adults and children from their public health insurance rolls. One year later, with the virus still raging, President Biden signed the American Rescue Plan to provide another form of support: temporarily increasing the child tax credit and expanding it to include more low-income families. Both provisions have expired, and the impact is now being tallied…