A presentation circulated internally within the Centers for Disease Control and Prevention (CDC) and newly obtained by multiple news outlets offers a much grimmer assessment of the delta variant than what the agency has been sharing publicly, with a few key discrepancies between their public and private messaging.
The document, obtained and reviewed by the New York Times and the Washington Post, which both reported on its contents Thursday night, draws on a combination of unpublished data from outbreak investigations and recent studies.
One of the biggest revelations from the slideshow, which was written by a doctor at the CDC and shared within the agency, is that it says the new evidence suggests vaccinated individuals infected with delta may be able to transmit Covid-19 as easily as those who are unvaccinated.
This differs from what CDC Director Dr. Rochelle Walensky said earlier this week, as she characterized virus transmission among vaccinated people as possible—but still rare—while announcing the agency’s new mask guidance.
The slideshow also offered new (and previously unshared) detail about the transmissibility of the delta variant, its risk of causing more severe illness and how it may also make people infectious for longer than other variants.
While CDC officials have labeled delta more infectious than other variants, the presentation explicitly deems it more transmissible than the viruses that cause MERS, SARS, Ebola, the common cold, the seasonal flu and smallpox, and as contagious as chickenpox.
Furthermore, the presentation says the delta variant appears more likely to lead to severe disease (upping the chances of hospitalization and requiring oxygen), which has been suggested by other public health officials but not explicitly outlined by the CDC, and that it may be infectious for 18 days instead of 13.
It also calls for universal masking “given higher transmissibility and current vaccination rates.”
The document notes this messaging differs from what the CDC has been sharing publicly and calls on the agency to “acknowledge the war has changed.”
While it offers a more dire review of the delta variant, the presentation highlights that vaccines still appear to be highly effective in preventing serious illness, hospitalization and death.
According to the Washington Post, Walensky privately briefed members of Congress on Thursday, drawing upon much of the material in the document. The CDC may also publish this data to the public soon, the reports say. However, some have questioned why the agency didn’t release this information earlier. Walensky referenced “unpublished data” when announcing the CDC’s decision to reimpose mask recommendations for vaccinated people in areas with high virus transmission, but it was not made public. The CDC did not immediately respond to a request for comment from Forbes and declined requests from other news outlets.
“CDC Recommends Masks Again—Including For Fully Vaccinated In Certain Places—Amid ‘Worrisome’ New Science About Delta Variant” (Forbes)
“‘The war has changed’: Internal CDC document urges new messaging, warns delta infections likely more severe” (The Washington Post)