The delta variant spreads much more easily than previous forms of the coronavirus. COVID-19 cases are surging. In late June, the U.S. saw days with fewer than 10,000 new cases. In late August, daily counts were as much as sixteen times that. Oregon has also seen cases multiply. Hospitals are seeing spikes in COVID patients. Vaccinated people can carry and spread the delta variant. Unlike with earlier forms of the virus, vaccinated people can carry high levels of delta in their nose and throat. They can also spread it. This is why Oregon returned to requiring masks indoors and now also requires masks in many outdoor public settings. It's also why the CDC changed its advice and now advises everyone to wear masks in indoor public settings in areas with substantial or high spread. The delta variant may cause more severe illness.