A field hospital in Brooklyn, N.Y., built to deal with the coronavirus has been closed without treating a single patient. The $21 million facility was part of Governor Andrew Cuomo’s response to the growing number of coronavirus patients at New York City hospitals. That response included smaller facilities at the Billie Jean King Tennis Center and Stony Point (Long Island), and a huge, 1,100-bed medical center at the Javits Center. All told, the state spent upwards of $350 million on facilities that were built but never used.