Biden aims to vaccinate 70% of American adults by July 4

President Joe Biden takes questions from reporters as he speaks about the COVID-19 vaccination program, in the State Dining Room of the White House, Tuesday. (AP Photo/Evan Vucci)

WASHINGTON — President Joe Biden set a new vaccination goal to deliver at least one shot to 70% of adult Americans by July Fourth as he tackles the vexing problem of winning over the “doubters” and those unmotivated to get inoculated.