CDC: Delta variant accounts for 83% of US cases

Updated: Jul 20, 2021 / 01:29 PM EDT

WASHINGTON, DC – JULY 20: Rochelle Walensky, Director of the U.S. Centers for Disease Control and Prevention (CDC) testifies during a Senate Health, Education, Labor, and Pensions Committee hearing at the Dirksen Senate Office Building on July 20, 2021 in Washington, DC. The committee will hear testimony about the Biden administration’s ongoing plans to deal with the COVID-19 pandemic and Delta variant. (Photo by Stefani Reynolds-Pool/Getty Images)

NEW YORK (NewsNation Now) — Health officials say the delta variant of the coronavirus continues to surge and accounts for an estimated 83% of U.S. COVID-19 cases.

That’s a dramatic increase from the week of July 3, when the variant accounted for about 50% of genetically sequenced coronavirus cases.

“The best way to prevent the spread of COVID-19 variants is to prevent the spread of disease, and vaccination is the most powerful tool we have,” said Dr. Rochelle Walensky, director of the Centers for Disease Control and Prevention, during a U.S. Senate hearing Tuesday.

The delta variant is a mutated coronavirus that spreads more easily than other versions. It was first detected in India but now has been identified around the world.

While most people getting infected are unvaccinated, a small percentage of fully vaccinated individuals are catching the delta variant of coronavirus.

An aide to House Speaker Nancy Pelosi and a White House official tested positive for COVID-19 Tuesday. They were attending a meeting with members of the Texas House Democratic delegation, which has had at least five members test positive for coronavirus.

Also at the hearing Dr. Anthony Fauci, the nation’s top infectious disease expert, angrily confronted Kentucky GOP Sen. Rand Paul, rejecting Paul’s insinuation that the U.S. helped fund research at a Chinese lab that could have sparked the COVID-19 outbreak.

Paul suggested that Fauci had lied before Congress when in May he denied that the National Institutes of Health funded so-called “gain of function” research — the practice of enhancing a virus in a lab to study its potential impact in the real world — at a Wuhan virology lab. U.S. intelligence agencies are currently exploring theories that an accidental leak from that lab could have led to the global pandemic.

The Associated Press contributed to this report.