CDC director: Delta variant accounts for 83 percent of all COVID-19 cases in US

The delta variant of the novel coronavirus is now responsible for 83 percent of all sequenced COVID-19 cases in the United States, Centers for Disease Control and Prevention (CDC) Director Rochelle Walensky said Tuesday.

That estimate is a major increase from just over two weeks ago. For cases tallied during the week of July 3, the CDC estimated the delta variant accounted for about 50 percent of new infections.

Walensky told the Senate Health Committee that in some parts of the country with low vaccination rates, the percentages are even higher.

Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, noted that the delta variant could be responsible for up to 90 percent of cases in some areas. 

Vaccination has been uneven across states, and only about half of all eligible people nationwide are fully vaccinated.

“We have the tools to end this epidemic,” Fauci said. “It’s up to us to use those tools.”

Health officials have described the latest stage of the coronavirus as a “pandemic of the unvaccinated” while emphasizing that those who have had their shots are relatively safe.

Walensky cited a five-month CDC study that found 99.5 percent of COVID-19 deaths are among people who are unvaccinated.

“Each death is tragic, and even more heartbreaking when we know the majority of deaths could be prevented with a simple, safe available vaccine,” Walensky said.

Arkansas, Missouri, Florida and Louisiana are the four states with the highest per capita new cases per day, according to data from the Covid Act Now tracking site. The percentage of the population with at least one shot in those states is 44 percent, 47 percent, 56 percent and 40 percent, respectively. 

By contrast, Vermont and Massachusetts, where the vaccination rate is more than 70 percent, are faring much better. 

Fauci and Walensky also told the panel that it’s still unclear when or if booster shots are needed, but clinical studies are being conducted to figure that out.

“Right now we are doing studies to determine whether or not we will need boosters to increase the durability of protection,” Fauci said. “We don’t want people to believe that when you’re talking about boosters, that means the vaccines aren’t effective. They are highly effective, we are talking about the durability of that.”  

Walensky added that she expects the immunity from vaccines to “wane not plummet,” but when the agency sees waning happening, “that will be our time for action.”