The delta Covid variant has spread so rapidly across the U.S. that most counties in the country now meet the CDC’s guidelines recommending people wear masks indoors — whether they are vaccinated or not. “We continue to see cases, hospitalizations and deaths increase across the country. And now, over 90% of counties in the United States are experiencing substantial or high transmission,” Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, told reporters at a briefing Thursday. “As we have been saying, by far, those at highest risk remain people who have not yet been vaccinated.” The CDC ... (full story)