Five under-vaccinated regions of the U.S. could be putting the entire nation at risk, according to researchers at Georgetown University. The fear is COVID-19 could mutate so significantly in these areas, it could defeat vaccines.

An analysis by Georgetown University researchers found five significant clusters in the southern and lower Midwestern part of the U.S. They include portions of Florida, Georgia, Alabama, Mississippi, Louisiana, Arkansas, Missouri, Oklahoma, Tennessee, Texas and New Mexico. 

The Biden administration is sounding the alarm about a rapid rise in the Delta variant, which is significantly more widespread than previously thought. 

“To be clear, there will likely continue to be an increase in cases among unvaccinated Americans,” said White House COVID-19 Response Coordinator Jeff Zients. 

A study published in the journal Nature on Thursday suggests that having only one dose of a vaccine offers little protection against the Delta variant. There are 25 million people in the U.S. who have received only one shot, and 140 million are unvaccinated, leaving 45% of the country at risk, according to the Centers for Disease Control and Prevention.

In Missouri, the Delta variant accounts for 73% of new COVID cases, according to the CDC. In Texas, a youth camp near Austin may be the nation’s latest super-spreader event. More than 100 cases have been confirmed, and officials fear the number may eventually top 200.

“We believe that this is an outbreak of the Delta variant,” said Dr. Philip Keiser, Galveston County’s local health authority. 

At Houston Methodist Hospital, the Delta variant is responsible for 42% of new cases. The hospital expects the Delta variant to make up 90% of its cases in the next two to three weeks. 

“The majority of patients that we are seeing hospitalized with COVID-19 with the Delta variant, the vast, vast majority of those patients are unvaccinated,” said Dr. Wesley Long, the director of medical microbiology at Houston Methodist Hospital. 

Dr. Anthony Fauci, the nation’s top infectious disease expert, said those who are most vulnerable and live in low vaccination areas should take precautions.

“If you are an elderly person or if you have a person with an underlying disease, you might want to go the extra mile of protection of wearing a mask if you are indoors,” he said Thursday.