CDC warns Delta variant is as infectious as chickenpox; vaccinated people can transmit

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ByKate Larsen KGO logo
Friday, July 30, 2021
CDC warns Delta variant is as infectious as chickenpox
The Delta variant surging across the U.S. appears to spread as easily as chickenpox, and may be more transmissible than Ebola and smallpox.

PALO ALTO, Calif. (KGO) -- The Delta variant surging across the U.S. appears to spread as easily as chickenpox and may be more transmissible than Ebola and smallpox - all of this according to an internal CDC document published by the Washington Post.

"We took two steps forward with the vaccines, but we're taking a big step back now," said Stanford's Dr. Yvonne Maldonado, who calls the latest data on the Delta variant "groundbreaking."

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Dr. Maldonado, a pediatric infectious disease specialist and CDC ACIP committee liaison, says because the Delta variant's virus levels are 1,000 times higher in the body than the original variant, it is twice as infectious.

"Now we know that even with vaccinated people, billions of viruses can be present in your nose in your mouth," she continued, "even if you're vaccinated, it's contagious."

That's why this week, the CDC said that even fully vaccinated people need to put their mask back on indoors in places where transmission rates are substantial or high - which is most of the country.

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Experts say unvaccinated neighborhoods across the Bay Area are driving most of the transmission fueling our fourth COVID-19 surge.

The updated advice in part comes from the 4th of July - Provincetown, Massachusetts outbreak - that has led to at least 882 COVID cases. Nearly three quarters of the cases in fully vaccinated people.

"I think we're going to head to a point soon, where everybody may get this virus or may be at risk for it. And if you're vaccinated, you are going to have few to no symptoms," said Dr. Maldonado.

The Delta variant may also be more deadly. But for vaccinated people, the CDC document says the risk of severe disease or death is reduced by at least 10-fold, which was always the goal of the vaccines.

Dr. Maldonado: "The real risk here, I think, is to people who can't get vaccinated, who are children under 12, and some immuno-compromised people."

Kate Larsen: "Dr. Maldonado, have you adjusted any of your behavior in recent weeks, because of all this news?"

Dr. Maldonado: "I'm still wearing a mask when I go anywhere indoors."

Dr. Maldonado says she always wears a surgical mask at the hospital, but when she un-masks to eat or drink, she distances herself from her colleagues, and so far that has been keeping her safe from the Delta variant in a high risk healthcare setting. In addition to masking, she suggests people think about going back to spending time with fully vaccinated pods of people and avoiding crowds, especially for unvaccinated children.

The CDC is expected publish additional data Friday.

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