Delta Variant May Cause 'Dense Outbreaks' in Parts of U.S. June 28, 2021 -- Some areas of the U.S. could see “very dense outbreaks” of the Delta coronavirus variant throughout the summer and fall, particularly in states with low vaccination rates, one expert said. The Delta variant, which was first identified in India, now makes up about 20% of new cases across the country. The variant has led to surges in parts of Missouri and Arkansas where people haven’t yet received a COVID-19 vaccine, according to CBS News. “It’s going to be hyper-regionalized, where there are certain pockets of the country where we can have very dense outbreaks,” Scott Gottlieb, MD, former commissioner of the FDA, said Sunday on CBS News’ “Face the Nation.”