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A CDC Document Gives New Details On Just How Dangerous The Delta Variant Really Is

Family members gather outside the window of a COVID-19 patient at Lake Regional Hospital in Osage Beach, Mo., on Monday.
Sarah Blake Morgan
/
AP
Family members gather outside the window of a COVID-19 patient at Lake Regional Hospital in Osage Beach, Mo., on Monday.

An internal slide presentation from the Centers for Disease Control and Prevention dated Thursday gives new details on how dangerous the delta variant really is.

One chart shows that it could be as contagious as chickenpox, which is one of the more transmissible viruses out there. It spreads more easily than the common cold, the 1918 flu and smallpox.

The document was first obtained and published by The Washington Post.

It also says that in addition to being more contagious, the delta variant likely increases the risk of severe disease and hospitalization, compared with the original strain.

A summary slide says that because of the delta variant, the agency should "acknowledge that the war has changed." It also recommends that the agency ramp up communications so the public will understand that vaccines still greatly reduce the risk of death and severe disease.

While most new infections are still occurring among unvaccinated people, the CDC estimates that 35,000 fully vaccinated Americans — out of more than 162 million — may get infected with the coronavirus every week.

Data from a July 4 outbreak on Cape Cod, in Massachusetts, appears to have led CDC Director Rochelle Walensky earlier this week to recommend that fully vaccinated people wear a mask indoors in public spaces if they live in areas where the spread of the virus is currently "substantial" or "high."

In that outbreak, vaccinated and unvaccinated people had nearly the same amount of virus recovered from test samples, indicating that vaccinated people are just as contagious as unvaccinated people when it comes to the delta variant.

With previous strains, vaccinated people who became infected with the coronavirus had much lower levels of virus, meaning they were less contagious.

That may have now changed.

The CDC has promised to release detailed data from this outbreak soon.

Copyright 2023 NPR. To see more, visit https://www.npr.org.

Joe Neel is NPR's deputy senior supervising editor and a correspondent on the Science Desk.
Rob Stein is a correspondent and senior editor on NPR's science desk.
Jane Greenhalgh is a senior producer and editor on NPR's Science Desk.