• The White House is deploying response teams across the U.S. focused on combatting the highly contagious delta variant, the Biden administration announced.
• The teams, comprised of officials from the Centers for Disease Control and Prevention and other federal agencies, will work with communities at higher risk of experiencing outbreaks, officials told reporters.
• There are 1,000 counties in the U.S. that have vaccination coverage of less than 30%, they said.

The White House is deploying Covid-19 response teams across the United States focused on combatting the highly contagious delta variant, the Biden administration announced Thursday.

The teams, comprised of officials from the Centers for Disease Control and Prevention and other federal agencies, will work with communities at higher risk of experiencing outbreaks and will focus on increasing the rate of Covid-19 vaccinations, White House Covid czar Jeff Zients said during a White House news briefing on the pandemic.

The teams will also increase testing to expand detection of the virus, facilitate contact tracing and provide therapeutics to help treat those who become infected, he said, adding the government is ready to provide additional personnel.

There are 1,000 counties in the U.S. that have vaccination coverage of less than 30%, CDC Director Dr. Rochelle Walensky said at the briefing. These counties, primarily in the South and Midwest, are the most vulnerable to the variant, she said.

"To be clear, the federal government stands ready to meet the moment and work with our state partners to respond to the delta variant," Zients said.

"As we continue to work with communities across the country to get more shots in arms, we will also be working with governors and state and local health authorities to identify and address the needs on the ground in places with emergency outbreaks," he added.

The Biden administration's comments come just ahead of the Fourth of July weekend, when many Americans are expected to gather for fireworks, barbeques and other large, in-person activities.

Delta, first identified in India but now in at least 96 countries, is expected to become the dominant variant of the disease in the U.S. The prevalence of the delta, estimated to be about 60% more transmissible than the alpha variant first found in the U.K., is doubling in the U.S. about every two weeks, according to the CDC.

Health officials say there were reports that the delta variant also causes more severe symptoms, but that more research is needed to confirm those conclusions. Still, there are signs the delta strain could provoke different symptoms than other variants.

This is a "highly contagious virus," said Dr. Paul Offit, a pediatrician and vaccine advocate who has served on advisory panels for both the CDC and the Food and Drug Administration.

"We need to vaccinate now. I mean get everyone vaccinated now because these mutations are going to continue to occur," he said. It's only July but "as we head into the fall and early winter you're going to see a surge and there are too many people in this country who are still unvaccinated."

Delta accounts for around 26% of Covid cases in the U.S., the CDC has estimated. Dr. Anthony Fauci, the White House's chief medical advisor, has called the variant the "greatest threat" to the nation's attempt to eliminate Covid-19.

The WHO has said the variant is the fastest and fittest coronavirus strain yet, and it will "pick off" the most vulnerable people, especially in places with low Covid vaccination rates. It recently urged everyone, including vaccinated people, to continue to wear masks as the variant spreads.

In some regions of the country, nearly one in two sequences is the delta variant, Walensky said Thursday. As the variant spreads, officials expect to see an increase in transmission unless states can vaccinate more people, she added.

As of Thursday, more than 181 million Americans, or 54.6% of the U.S. population, have had at least one dose of a Covid vaccine, according to data compiled by the CDC. More than 155 million Americans are fully vaccinated, according to the CDC.

"The delta variant is predicted to be the second most prevalent variant in the United States, and I expect that in the coming weeks it will eclipse the alpha variant," she said, urging those with symptoms to get tested for Covid.