The COVID-19 vaccine may become available before the end of the year — a long awaited milestone in the coronavirus pandemic for some, and a source of worry for others. More than a third of Americans, 35%, said they wouldn’t get a free U.S. government-approved vaccine if it were ready today, according to a recent Gallup survey. Previous polls found many people who were reluctant to get immunized worried about the safety of a vaccine that’s being developed with unprecedented speed.