According to an internal document from the US CDC, the Delta Covid variant increasing across the United States appears to cause more severe illness and spread as easily as chickenpox. The document is a slide presentation in which unpublished data is shown that fully vaccinated people might spread this variant at the same rate as unvaccinated people. The authenticity of the document was confirmed by CDC Director Dr Rochelle Walensky. The document 1st reported by The Washington Post.

According to Rochelle, “I think people need to understand that we’re not crying wolf here. This is serious. “It’s one of the most transmissible viruses we know about. Measles, chickenpox, this — they’re all up there.” The CDC is supposed to publish data Friday that will back Rochelle’s controversial decision to change guidance for fully vaccinated people. She said Tuesday the CDC recommended that in places where transmission of the virus is sustained or high, even fully vaccinated people should wear masks.


Rochelle said everyone in school staff, students, and visitors should wear masks. “The measures we need to get this under control — they’re extreme. The measures you need are extreme. It was the synthesis of the data all in one place that was sobering,” she said.

According to the CDC presentation, the Delta variant is as transmissible as chickenpox, with each infected person infects eight or nine others on average. The original lineage was as transmissible as the common cold. If vaccinated people get infected, they have as much virus in their bodies as unvaccinated people. This means they can also infect others like unvaccinated people.

90% of the severe disease can be prevented by vaccines but may be less effective at preventing transmission and infection, the document reads. Therefore more community spread and more breakthroughs despite vaccination. It says vaccines reduce death 10-fold or the risk of severe disease or and reduce the risk of infection three-fold. The presentation also has three reports that show the Delta variant might cause more severe disease. The virus is once again increasing across the US, especially in areas where fewer people are vaccinated.