The fast-spreading delta coronavirus variant is thought to be significantly more widespread than the CDC currently projects, two senior Biden administration health officials told Politico.
The delta variant, first detected in India, accounted for more than half of all new COVID-19 cases between June 20 and July 3, according to CDC data updated July 6. But officials said the actual number is likely much higher because states and private labs are taking weeks to report results to the CDC.
"It is everywhere now," an 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."
Genetic sequences from Scripps Research's outbreak.info suggest that the strain accounted for as much as two-thirds of new U.S. infections over the last two weeks, reports Politico. The site notes the data "may not represent the true prevalence of the mutations in the population."
Fifty-one percent is the CDC's "best estimate at this point," Rochelle Walensky, MD, director of the CDC, said July 8, adding that "it has some uncertainty around it."
"Although we expected the delta variant to become the dominant strain in the U.S., this rapid rise is troubling," Dr. Walensky said. "We know that the delta variant has increased transmissibility and it is currently surging in pockets of the country with low vaccination rates."