Delta Variant Soars, Becoming Dominant Cause of New COVID Cases in U.S.

The COVID-19 Delta variant, which is much more infectious and possibly more lethal than other strains, now accounts for over half of all new COVID cases in the United States, according to new data from the Centers for Disease Control and Prevention (CDC). The Delta variant, or B.1.617.2, jumped from 30.4% of new cases for the 2-week period ending June 19, to 51.7% of new cases between June 20 and July 3, Jade Fulce, a CDC public affairs spokesperson, tells Infection Control Today^® (ICT^®) in an email.

“In five HHS regions, B.1.617.2 (Delta) is predicted to be the predominant lineage, with proportions ranging from 34% to greater than 80%,” Fulce said. Forecasting the just what a variant will do and when it will do it amounts to trying to hit a moving target, with other moving targets often getting in the way.

“Variant proportions are dynamic and difficult to predict due to reporting delays, the presence of multiple variants, and changing incidence” Wade told ICT^®. “CDC continues to evaluate approaches that can reliably predict these dynamics while making improvements to genomic surveillance to increase the number, representativeness, and timeliness of specimens.”

The predominance of the Delta variant comes as the COVID-19 vaccination effort in the U.S. seems to have stalled. More than 172 million Americans, or about 67% of the adult population, have received 1 dose of the vaccine. About 156 million Americans, or 47% of the adult population have received both doses of the vaccine. CDC experts have said that anywhere from 70% to 85% of Americans would need to be vaccinated against COVID-19 to reach herd immunity.

As Fulce mentioned, the Delta variant appears to be running rampant in areas where COVID-19 vaccination rates are lowest. Yesterday at a White House press briefing, President Biden pleaded that all Americans get vaccinated. “Right now, as I speak to you, millions of Americans are still unvaccinated and unprotected,” Biden said. “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” now being responsible for over half of new cases.

Biden continued: “It seems to me that it should cause everybody to think twice. And it should cause reconsideration, especially in young people who may have thought that they didn’t have to be vaccinated, didn’t have to worry about it, didn’t have to do anything about it up to now.”

Eric Topol, director and founder of the Scripps Research Translational Institute, tells Axios that “we’ve hit the wall in the number of vaccinations in recent weeks. Just trying to deduce from other countries where we’re headed, if we don’t get a big jump up in our vaccination rate, we’re going to be vulnerable for a lot more cases.”

Rochelle Walensky, MD, the head of the CDC, starkly laid out just how much of a threat the Delta variant poses in a press conference at the White House on June 22. In essence, Walensky said that we need to stop the Delta variant now through vaccination, or risk facing something worse. While the vaccines work against the Delta variant, the variant “represents a set of mutations that could lead to future mutations that evade our vaccine. And that’s why it’s more important than ever to get vaccinated now, to stop the chain of infection, the chain of mutations that could lead to a more dangerous variant.”