Experts ?extremely worried? about Delta variant as US death toll hits 600,000

Delta is estimated to be 50 percent to 60 percent more contagious than Alpha.In the UK, infections with the Delta variant began popping up at very low levels in early April and then rose swiftly. The US Centers for Disease Control and Prevention on Monday officially dubbed Delta a "variant of concern.""Right now, in the United States, [Delta accounts for] about 10 percent of infections. At the end of May, researchers at Public Health England posted data (which had not been peer reviewed) indicating that two doses of the Pfizer-BioNTech vaccine were 88 percent effective at preventing a symptomatic infection with the Delta variant. Experts emphasized the importance of not skipping the second dose.)Data out of Scotland Monday likewise suggested that two doses of the Pfizer-BioNTech vaccine were 79 percent effective against the Delta variant, while two doses of Oxford-AstraZeneca vaccine were again 60 percent effective.Also on Monday, PHE released another analysis (also not peer reviewed) that finds that two doses of the Pfizer-BioNTech vaccine were 96 percent effective against hospitalization and two doses of the Oxford-AstraZeneca vaccine were 92 percent effective against hospitalization.“So we have the tools to control this and defeat it,” Gottlieb noted.But experts are still concerned.