He pledged to keep schools open, even if someone at any given school was found to have contracted the disease, saying that they would take a day to isolate the sick and clean the school before getting it back up and running. “If you’re under 50 and you’re healthy, which is most New Yorkers, there’s very little threat here.”

Three days later, facing (to use a favorite de Blasio-ism) “a very different reality,” including a growing outcry from parents and from his own public-health officials, some of whom threatened to quit if he didn’t shutter schools and start taking the outbreak more seriously, New York City public schools were officially closed, probably for the rest of the school year.

Shortly thereafter, he declined to cancel St. Patrick’s Day parade and then did. He resisted calls to cancel regular street sweeping and then did. He had a photo op at a 311 call center, where he told a caller who had just returned from Italy that she did not need to self-quarantine, advice that forced 311 to actually call the woman back and tell her to stay inside for 14 days. The mayor touted the city’s new, wide-scale testing capacity, only to have his Health Department announce that only hospitalized patients should be tested. He tweeted at Elon Musk to supply the city with ventilators. When a New York Times reporter wrote of his own gut-wrenching story about contracting COVID-19 and being unable to get help, a top mayoral aide chastised him online for seeking help at all rather than just getting better at home. And the mayor himself told a radio host that people who don’t display symptoms can’t transmit the disease, an assertion that contradicts information from the Centers for Disease Control and Prevention.