States like Alabama, Arkansas and Oklahoma are now rapidly administering covid shots.
In those states, less than half of the population has gotten at least one dose, below the national average of 58 percent, and hospitals are running out of beds and staff to treat those in need.
Biden administration officials said they believed the trend is driven by residents in the hardest-hit states seeing the effects of the virus first-hand, and growing concern about the risk the delta variant poses to younger adults and children.
Over the last 24 hours, the U.S. saw the highest number of daily shots administered since July 3, with 864,000 vaccinations administered.
