According to a new U.S. census estimate, some 30 million American adults who are open to getting a Covid vaccine have not yet managed to actually do so. Their ranks are larger than the hesitant — more than 28 million who said they would probably or definitely not get vaccinated, and than the 16 million who said they were unsure. … They are, for the most part, America’s working class, contending with jobs and family obligations that make for scarce discretionary time.