BOSTON — Nearly 2,000 doses of a COVID-19 vaccine were spoiled at a Veterans Affairs hospital in Boston after a contractor accidentally unplugged a freezer, hospital officials announced Thursday. Staff at the Jamaica Plain VA Medical Center discovered on Tuesday that a freezer had failed, compromising 1,900 doses of the Moderna COVID-19 vaccine. The plug to the freezer was found to be loose after a contractor accidentally unplugged it while cleaning, according to a statement from Kyle Toto, a spokesperson for VA Boston Healthcare System.