Washington (CNN)The Delta coronavirus variant surging across the US appears to cause more severe illness and spreads as easily as chickenpox, according to an internal document from the US Centers for Disease Control and Prevention obtained by The Washington Post.
The document — a slide presentation — outlines unpublished data that shows fully vaccinated people might spread the Delta variant at the same rate as unvaccinated people, according to the Post.
A federal health official told the newspaper that the data, which is expected to be released Friday, played a large role in the CDC’s updated mask guidance, which recommends that fully vaccinated people wear masks indoors when in areas with “substantial” and “high” transmission.
News of the document comes against the backdrop of rising coronavirus cases nationwide. The US averaged more than 61,300 new daily cases over the last week — an average that’s generally risen since the country hit a 2021 low of 11,299 daily cases on June 22, according to Johns Hopkins University data.
As of Wednesday, cases have risen in all but one state in the past seven days compared with the week before, according to Johns Hopkins.
CDC Director Dr. Rochelle Walensky told CNN’s “New Day” Wednesday that “with prior variants, when (vaccinated) people had these rare breakthrough infections, we didn’t see the capacity of them to spread the virus to others.”
But, outbreak investigations conducted in the last couple weeks showed vaccinated people who contract the highly contagious Delta variant “can actually now pass it to somebody else,” Walensky said.
The CDC document walks through new “communication challenges” as a result of breakthrough infections, along with the need to retool public health messaging to highlight vaccination as the best defense against the Delta variant, the Post reported.
Earlier Thursday, President Joe Biden announced a number of new steps his administration will take to try to get more Americans vaccinated, including requiring that all federal employees must attest to being vaccinated against Covid-19 or face strict protocols.
“This is an American tragedy. People are dying — and will die — who don’t have to die. If you’re out there unvaccinated, you don’t have to die,” Biden said during remarks at the White House. “Read the news. You’ll see stories of unvaccinated patients in hospitals, as they’re lying in bed dying from Covid-19, they’re asking, ‘Doc, can I get the vaccine?’ The doctors have to say, ‘Sorry, it’s too late.'”
This story has been updated with additional background.