A new data analysis by researchers at Georgetown University pinpoints a number of undervaccinated clusters of the United States that pose a significant threat to the nation's—and potentially the world's—gradual progress against the Covid-19 pandemic, particularly given their potential to serve as "factories" for extremely contagious variants such as the now-dominant Delta strain.
The five most significant clusters identified by the Georgetown researchers are largely located in the southern U.S., in states such as Georgia, Alabama, Arkansas, Tennessee, Mississippi, and Louisiana—all of which are currently experiencing a rise in coronavirus cases as Delta rips through communities concentrated with people who have yet to receive a single vaccine shot. Those clusters include more than 15 million people.
"The group of counties in each cluster... together have lower vaccination coverage than expected, and make up a large population size. All of the top five clusters are focused in the southeastern U.S.," the researchers note.
"The more geographically clustered unvaccinated individuals are," the analysis continues, "the higher the chance that an unvaccinated individual will interact with another unvaccinated individual, and the higher the chance that a disease transmission event will occur. Low vaccination clusters, therefore, are locations where risk of transmission of Covid-19 remains high (in the absence of social distancing and masking)."
Because "variant emergence stems from disease transmission," the report notes that every new transmission of the disease "creates an opportunity for a new variant to transmit to another host and take hold in a population.
Therefore, the researchers write, "curbing transmission events is our best recourse to prevent variant emergence."
Dr. Jonathan Reiner, a CNN medical analyst and professor of medicine and surgery at George Washington University, said Thursday that "these clusters of unvaccinated people are what is standing in the way of us putting this virus down permanently."
"We've been lucky with the variants so far that they've been relatively susceptible to our vaccine," Reiner added, "but the more you roll the dice, the more opportunities there will be for a resistant variant."
The Georgetown analysis came as the Biden administration announced a new initiative aimed at intensifying the U.S. vaccination drive as inoculation rates continue to slow across the country. According to the New York Times, "Providers are administering about 0.73 million doses per day on average, about a 78 percent decrease from the peak of 3.38 million reported on April 13."
In a speech earlier this week, President Joe Biden said the effort will emphasize tackling hesitancy and increasing access by "getting the vaccines to more and more family doctors and healthcare providers so more Americans can get this shot at their doctor's office from the folks that they know and they trust the most."
"Our fight against this virus is not over," the president said. "Right now, as I speak to you, millions of Americans are still unvaccinated and unprotected. And because of that, their communities are at risk. Their friends are at risk. The people they care about are at risk. This is an even bigger concern because of the Delta variant."
According to the Centers for Disease Control and Prevention, the Delta strain—which is estimated to be 60% more transmissible than the previously dominant Alpha mutation—accounted for more than half of all new coronavirus infections in the U.S. between June 20 and July 3 as it sweeps across the country and the globe.
But Politico reported Thursday that Biden administration officials believe the Delta mutation is "significantly more widespread" in the U.S. "than the current federal projections."
"It is everywhere now," one unnamed official told Politico. "The risk really is in the unvaccinated community. We're starting to see more and more people get sick and need medical attention."