The U.S. Centers for Disease Control and Prevention, or CDC, recommended Tuesdaythat fully vaccinated Americans wear face-coverings in areas "with substantial and high transmission" of COVID-19.The CDC also advised all K-12 students, teachers, workers, and visitors to wear a face-covering, or mask.The recommendation is in effect for both unvaccinated and vaccinated people.The health agency said the highly infectious Delta variant has led to a large increase of coronavirus cases in parts of the country.The variant now represents more than 80 percent of new cases, especially in areas where fewer people are vaccinated.The CDC's investigation also showed that, in rare cases, some vaccinated people infected with the Delta variant may "spread the virus to others."CDC Director Rochelle Walensky added, "This new science is worrisome and, unfortunately, warrants an update to our recommendation."The recommendation marked a sharp change of the CDC's position from two months ago.
