CHICAGO — The number of new coronavirus cases confirmed in the United States has steadily declined in recent days. In New York, the figure has dropped over the past month. The numbers have also plunged in hard-hit Massachusetts and Rhode Island, and some states, including Vermont, Hawaii and Alaska, are reporting few new cases at all. But that progress is tenuous and uncertain. The nation has reached a perilous moment in the course of the epidemic, embracing signs of hope and beginning to reopen businesses and ease the very measures that slowed the virus, despite the risk of a resurgence. With more than two-thirds of states significantly relaxing restrictions on how Americans can move about over the last few weeks, an uptick in cases is widely predicted. Months after the virus began spreading, only about 3 percent of the population has been tested for it, leaving its true scale […]