The Centers for Disease Control and Prevention (CDC) warned in an internal document that the delta variant of the coronavirus appears to spread as easily as chickenpox and likely causes more severe illness.
The document, which was first obtained by the Washington Post, says that officials must "acknowledge the war has changed" against COVID-19. The CDC confirmed the existence of the document to Spectrum News.
The document states that an infected person can spread the delta variant to 8 or 9 people on average, compared to the original strain of COVID-19, which each infected person could spread to about one or two people on average – about as transmissible as the common cold. Vaccinated people who get infected with delta have similar viral loads compared to those who contract delta and are unvaccinated.
The document notes that the delta variant, which was first detected in India, causes infections that are more contagious than the common cold, flu, smallpox and Ebola virus.
"I think people need to understand that we're not crying wolf here," CDC director Dr. Rochelle Walensky told CNN. "This is serious."
"It's one of the most transmissible viruses we know about. Measles, chickenpox, this – they're all up there," she added.
At the current rate, the document noted, there are 35,000 symptomatic infections per week among 162 million vaccinated Americans.
However, the CDC noted that the risk of infection is reduced threefold in people who are fully vaccinated – and the risk of severe illness and death is reduced tenfold.
Vaccines, they said, prevent greater than 90% of severe disease, but may be less effective at preventing transmission or infection, leading to a greater risk of community spread.
The document outlined a number of prevention strategies, including universal masking to slow the spread of delta, as well as encouraging leaders to consider vaccine mandates, particularly for health care workers.
President Joe Biden on Thursday announced that all federal employees and onsite contractors must attest to their COVID-19 vaccination status or face regular testing and strict masking, social distancing and travel restrictions.
Later Thursday, the Department of Defense said it will ask all U.S. military and civilian DOD personnel to provide their COVID-19 vaccination status and will move forward with making vaccination a requirement.
“Personnel unable or unwilling to do that will be required to wear a mask, physically distance, comply with regular testing requirement and be subject to official travel restrictions,” Deputy Pentagon Press Secretary Jamal Brown said in the release.
Also this week, the Department of Veterans Affairs announced it will require many of its frontline medical workers to be vaccinated against COVID-19, becoming the first federal agency to do so, "because it’s the best way to keep Veterans safe, especially as the Delta variant spreads across the country," Veterans Affairs Secretary Denis McDonough said.
"Whenever a Veteran or VA employee sets foot in a VA facility, they deserve to know that we have done everything in our power to protect them from COVID-19. With this mandate, we can once again make — and keep — that fundamental promise," McDonough said in a statement.
The report comes on the heels of the CDC changing its mask guidance this week, recommending that fully vaccinated Americans wear masks indoors in some parts of the country, citing the delta variant. The agency recommended that people who are vaccinated should wear masks indoors in parts of the U.S. where COVID-19 is surging, notably in areas classified as having "substantial" and "high" transmission of the coronavirus, as noted by county level on the CDC's website.
In recommending that vaccinated people resume wearing masks indoors in virus hot spots, the CDC this week said that new evidence shows that breakthrough infections may be as transmissible as those in unvaccinated people. They cited a large recent outbreak among vaccinated individuals in the Cape Cod town of Provincetown, Massachusetts, among others, for the change.
The Associated Press contributed to this report.