"Please get vaccinated now," Biden said. "It works. It's free. It's never been easier, and it's never been more important."
The Delta variant, which is becoming dominant in many countries, is more easily transmitted than earlier versions of the coronavirus and may cause more severe disease, especially among younger people. It has now been found in every U.S. state, health officials have said.
Biden noted that studies have shown that since early May virtually every COVID-19 hospitalization or death in the United States had been among people who were not vaccinated.