Nurses Assistant Vanessa Gutierrez, left, and Jamie McDonough, RN, talk to a COVID-19 patient in the COVID ICU at St. Joseph Hospital in Orange, CA on Wednesday, July 21, 2021. COVID-19 cases have risen in recent weeks due, in part, to the delta variant.

  • An internal CDC slideshow obtained by The Washington Post warns of the threat of the delta variant.
  • The data cited by the document influenced the CDC's decision to reverse its mask policy on Tuesday, a source told The Post.
  • Early evidence shows that that the delta variant can still be spread among fully vaccinated people.
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According to an internal presentation from the Center for Disease Control and Prevention obtained by The Washington Post, the delta variant is more infectious than Ebola, the common cold, and smallpox.

Based on unpublished data recently collected from outbreak investigations and studies, the document also noted early evidence, which shows people who have been fully vaccinated can pass on the delta variant just as easily as those who are unvaccinated.

One slide also discussed how older people have a higher risk of hospitalisation and death, regardless of their vaccination status.

However, vaccines do protect people from non-delta Covid-19 infections by up to three times, it said.

The CDC on Tuesday recommended that everyone should mask up while indoors, including those who have been fully vaccinated. It was a reversal from its policy in May when it said masks were no longer necessary for those who had finished taking their shots.

An anonymous federal health official told The Post that the data cited in the slideshow played a key role in the CDC's recent decision and that the information would be published in full on Friday.

"Although it's rare, we believe that at an individual level, vaccinated people may spread the virus, which is why we updated our recommendation," the official said. "Waiting even days to publish the data could result in needless suffering, and as public health professionals, we cannot accept that."

The internal document also said that the delta variant's symptoms are likely more severe than earlier Covid-19 variants afflicting the world. It cited reports in Canada and Scotland, where people infected by the variant have higher odds of needing hospitalisation, and Singapore, where delta infections have produced an increased demand for oxygen requirements and intensive care admissions.

Still, vaccines protect people from severe disease and death by up to 10 times, said the document.

For cases that don't involve the delta variant, it is "expected" but rare for the virus to be transmitted through vaccinated people, which is also called a breakthrough case, the slideshow said.

But it also highlighted that the CDC needs to amp up its messaging of the vaccine's efficacy and usefulness in mitigating the pandemic.

One of the center's next steps, one slide says, is to "acknowledge that the war has changed." It also suggested considering vaccine and face mask mandates to protect those especially vulnerable to the virus and to control the pandemic's spread.

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