New Covid boosters are set to be rolled out as early as next Wednesday — after tests showed they trigger protection against new variants. The director of the Centers for Disease Control and Prevention, Mandy Cohen, is expected to sign off on the shots on September 13, making them available. CDC experts are yet to say who will be offered the updated vaccines, but the White House previously suggested they would be made available to all age groups. Only 17 percent of Americans have come forward to get a single updated booster since the two-dose regimen was expanded, amid growing...