ATLANTA — The Centers for Disease Control and Prevention released a new strategy on mask wearing Friday that will allow most people to ditch masks in most indoor settings, including classrooms. The agency now says masks are needed in public indoor settings, including schools, only in counties where COVID-19 cases are straining the health care system. The transmission rate will be calculated using three metrics: new COVID hospitalizations, current hospitalizations and new COVID infections. Guidelines will hinge less heavily on new infections, which had rocketed to new highs during the recent ou…