CDC urges vaccinated people in covid hot spots to resume wearing masks indoors

Meanwhile, the alpha variant, first seen in the United Kingdom, became the dominant strain across the country. But in June, the delta variant began to spread at exponential rates, said scientist William Lee of the genomics company Helix. Lee said Tuesday he estimates it now accounts for more than 90 percent of infections nationally. The alpha variant, by contrast, is seen in only about 3 percent of positive tests. “It’s almost gone,” he said.