ATLANTA, Ga. -- The delta variant that’s now the dominant strain of coronavirus in the U.S. appears to be as transmissible as chickenpox, according to an internal document from the Centers for Disease Control and Prevention (CDC).
CDC Director Dr. Rochelle Walensky confirmed the authenticity of the document to CNN, adding that the coronavirus is “one of the most transmissible viruses we know about.”
Along with comparing the delta variant’s transmissibility to chickenpox, the CDC says in the document that the strain is more transmissible than MERS & SARS, Ebola, the common cold, the Spanish flu, and smallpox.
The Washington Post was the first outlet to report on the document, which is a slideshow that outlines unpublished data about how fully vaccinated individuals may spread the delta variant at about the same rate as unvaccinated people.
The document also outlines some next steps for the CDC as it continues to combat rising case rates in parts of the country, largely among the unvaccinated. In one line about communications, the CDC writes that officials must “acknowledge the war has changed.”
The CDC also writes that it must improve the public’s understanding of breakthrough infections, as well as improve communications around individual risk among those who are vaccinated.
“Risk of severe disease or death reduced 10-fold or greater in vaccinated,” wrote the CDC. “Risk of infection reduced 3-fold in vaccinated.”
The document also states that the CDC should consider vaccine mandates for health care personnel to protect vulnerable populations and universal masking for “source control and prevention.”
The news of this document comes days after the CDC updated its mask guidance to say that vaccinated Americans should wear masks indoors again in areas where there is “substantial and high transmission” of the coronavirus.
The CDC also said Tuesday that everyone in K-12 schools should wear masks, regardless of their vaccination status, including students, staff, and visitors.
The CDC director said that the agency decided to change its mask recommendations because of new data that shows some people infected with the delta variant can spread the virus to others even after they’ve been vaccinated.
“In recent days, I have seen new scientific data from recent outbreak investigations showing that the delta variant behaves uniquely differently from past strains of the virus that cause COVID-19,” said Walensky. “Information on the delta variant from several states and countries indicates that in rare occasions, some vaccinated people infected with the delta variant after vaccination may be contagious and spread the virus to others. This new science is worrisome and unfortunately warrants an update to our recommendations.”
The CDC is continuing to encourage Americans to get vaccinated against COVID-19. Officials say the vaccines are effective against severe disease and death from variants of the virus that causes COVID-19 currently circulating in the country, including the delta variant.
“Infections happen in only a small proportion of people who are fully vaccinated, even with the delta variant. When these infections occur among vaccinated people, they tend to be mild,” the CDC says on its website.