The COVID-19 delta variant currently surging across the U.S. is about as transmissible as chickenpox and can cause much more serious infections, according to an internal report from the CDC, per The New York Times.

  • The unpublished data supports the CDC’s controversial decision to change mask guidelines for vaccinated people, reported CNN.
  • This week, the CDC changed its guidelines to urge vaccinated people to wear masks indoors in areas of “substantial” or “high” transmission, reported the Deseret News.

Here’s what we know right now.

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What did the unpublished CDC data say about the COVID-19 delta variant?

The internal CDC report — a slideshow — provided data on the transmissibility of the delta variant and recommendations for the CDC going forward, reported The New York Times.

  • CDC Director Dr. Rochelle Walensky confirmed the document as authentic, per CNN.
  • The CDC planned to publish the data about the delta variant on Friday but The Washington Post published the internal report Thursday evening, reported CNN.

The internal CDC report offered a grim description of the COVID-19 delta variant. According to the document:

  • The delta variant has a longer window of transmission than previous variants, per CNBC.
  • Vaccinated people can spread the delta variant just as easily as unvaccinated people, per The New York Times.
  • Vaccinated people are still safer and protected from more serious disease — even against the delta variant, per CNN.
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How transmissible is the COVID-19 delta variant?

The original COVID-19 strain, alpha, was about as transmissible as the common cold. On average, each infected person infected about two others, per CNN. The new delta strain is much more transmissible.

  • The new delta variant is about as transmissible as chickenpox with each infected person, on average, infecting eight or nine others, per CNN.
  • “It’s one of the most transmissible viruses we know about,” said Walensky per CNN.

The delta variant is “more transmissible than the common cold, the 1918 Spanish flu, smallpox, Ebola, and MERS and SARS,” according to the CDC document, per CNBC.

People can carry “enormous” amounts of the delta variant virus in their nose and throat — regardless of vaccination status, reported The New York Times. Comparatively, infected people carry one thousand times more of the delta variant than the alpha variant.

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What else did the CDC report recommend?

The internal CDC document recommended stricter COVID-19 prevention measures than the CDC publicly announced this week, reported CNBC.

  • The CDC report recommended vaccine mandates, per CNN.
  • The internal document recommended universal mask requirements, per CNBC.

“The measures we need to get this under control — they’re extreme,” said Walensky to CNN. “I think people need to understand that we’re not crying wolf here. This is serious.”

  • “The war has changed,” according to the report, per CNBC.
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