Federal health officials sounded the alarm Friday about a fast spreading, far more contagious variant of the coronavirus that is projected to become the dominant source of infection in the country by March, potentially fueling another wrenching surge of cases and deaths. In a study released on Friday , the Centers for Disease Control and Prevention said that its forecasts indicated outbreaks caused by the new variant could lead to a burgeoning pandemic this winter. It called for a doubling down on preventive measures, including more intensive vaccination efforts across the country. The variant is not known to be more deadly or to cause more severe disease. But the dire warning — hedged by limited data about just how prevalent the variant first identified in Britain has become — landed in a week where the nation’s nascent vaccination campaign was hampered by confusion and limited supplies as demand grew […]