The rapid spread of the delta variant of the coronavirus is poised to divide the United States again, with highly vaccinated areas continuing toward post-pandemic freedom and poorly vaccinated regions threatened by greater caseloads and hospitalizations, health officials warned this week.
The highly transmissible strain is taxing hospitals in a rural, lightly vaccinated part of Missouri and caseloads and hospitalizations are on the rise in states such as Arkansas, Nevada and Utah, where fewer than 50 percent of the eligible population has received at least one dose of vaccine, according to data compiled by The Washington Post.
One influential model, produced by the Institute for Health Metrics and Evaluation at the University of Washington, predicts a modest overall surge in cases, hospitalizations and deaths this fall. Scott Gottlieb, a former head of the Food and Drug Administration, said Sunday that a fall surge could occur even if 75 percent of the eligible population is vaccinated.
But experts think that most damage will occur in localized pockets where large numbers of people have declined to be vaccinated or have not gained access to the shots.
I think a rise in cases is certainly going to happen, said William Hanage, an associate professor of epidemiology at the Harvard T.H. Chan School of Public Health. The question is how large a rise and how consequential it’s going to be.
Those under-vaccinated communities are more likely to be severely affected, he said.
At a briefing by the White House Covid-19 Response Team on Tuesday, Anthony S. Fauci, the nation’s top infectious-disease specialist, said that there is a danger — a real danger — that if there is a persistence of a recalcitrance to getting vaccinated, that you could see localized surges, which is the reason why I want to emphasize what all four of us have said: All of that is totally and completely avoidable by getting vaccinated.
Resistance is greatest among younger people. Just 38.3 percent of people ages 18 to 29 have been vaccinated, according to federal research released Monday. Across all age groups, people living in counties with high rates of poor and uninsured people and less access to computers and the Internet were less likely to be vaccinated, the research showed.
In general, rural and Republican areas have embraced vaccination less than cities and Democratic states in the Northeast and along the West Coast. All of the states in New England have given at least one dose to 61 percent of their residents or more. In San Francisco, 65 percent of residents are fully vaccinated.
Overall, the nation has made significant progress against the virus. The seven-day average of new daily cases has plummeted to 10,350 and deaths are down to an average of 273 each day, Rochelle Walensky, director of the Centers for Disease Control and Prevention, reported Tuesday. Those figures are a small fraction of average daily peaks of nearly 250,000 cases and 3,300 deaths in January.
In addition, with 80 percent of adults older than 65 vaccinated, the most vulnerable population is largely protected. That should mean many fewer deaths and hospitalizations even if another widespread surge were to occur this fall or winter.
But the delta variant, which is much more transmissible and causes more severe illness than previous versions of the virus, is taking over the United States with stunning speed, as it did in India, where it was first identified, and later the United Kingdom. It has doubled as a percentage of new infections every two weeks, Fauci said, from 1.2 percent of new infections on May 8 to 20.6 percent this week. Officials expect it to soon become the dominant strain in the United States.
Helix, a lab company working with the CDC to sequence samples, also concluded that the delta variant and the gamma variant first identified in Brazil are rapidly replacing the alpha variant, which was first identified in the United Kingdom and took over in a matter of months, according to research the company posted this week. The work has not yet been reviewed by experts not involved in the study.
The delta variant may accomplish the same thing within weeks.
It has come out of nowhere, said Mark Pandori, who runs the genomics lab at the University of Nevada at Reno. It seems to be a very successful variant and is closing in on the number one spot.
Pandori emphasized that the number of positive cases is very low, as they are in many other parts of the country, and that the small number of breakthrough infections among those who have been vaccinated appears to confirm the immunizations’ effectiveness against current variants, including delta.
Pavitra Roychoudhury, a virologist at the University of Washington, said cases in the state have been almost exclusively caused by the alpha variant for several months. But in the past two weeks, cases of both the delta variant and the gamma variant have been increasing.
Karthik Gangavarapu, a researcher at the Scripps Research Institute in San Diego who works on genomic epidemiology, predicted that the delta variant may comprise more than 50 percent of cases by July, based on the volume that state labs are seeing. He said the numbers appear to confirm early studies that the variant may be 40 to 60 percent more transmissible than the alpha variant, which is already more transmissible than the original virus that emerged from Wuhan, China.