Internal CDC Report Calls Delta Variant As Contagious As Chicken Pox

An internal CDC report is sounding the alarm about how contagious the delta variant is — in both unvaccinated and vaccinated people

As the delta variant of COVID-19 continues to spread, scientists at the CDC are sounding some serious alarms. On Tuesday, center director Dr. Rochelle P. Walensky acknowledged that delta is much more contagious, more likely to break through vaccine protection, and may cause more severe illness than all other previously known variants of the coronavirus. She also noted that vaccinated people seem to carry just as much of the delta variant virus in their nose and throat as unvaccinated people, and therefore likely contribute to its spread.

But an internal CDC document, first reported on by the Washington Post on Thursday, shows just how alarmed scientists are becoming at what they’re learning about delta. The document shows the variant, first detected in India, is more contagious than the viruses that cause MERS, SARS, Ebola, the common cold, the seasonal flu, and smallpox. It’s suspected to be as contagious as chickenpox, according to the document.

“The C.D.C. is very concerned with the data coming in that Delta is a very serious threat that requires action now,” an unnamed CDC official told the New York Times. The agency is expected to publish additional public information on the variant today, after the leaked internal document said the next step for the CDC is to “acknowledge the war has changed.”

One of the most alarming things the report noted was that around 35,000 symptomatic infections were being recorded weekly among vaccinated people as of July 24. The report didn’t track all mild or asymptomatic infections, so the actual rate of breakthrough infections in vaccinated people is almost certainly higher than that.

The U.S. reached a daily average case rate of more than 71,000 on Thursday, a massive increase from earlier in the year, when vaccinations were at their peak and cases fell sharply. Delta has now reversed much of that progress, though the country is still far below the case numbers recorded during the devastating peak of the virus last winter. New data cited in the CDC’s internal report states that transmission by vaccinated people, previously thought to be rare, is likely much more common than scientists had hoped, and contributing to the spread of the delta variant.

The CDC has already recommended that all people, even those who are vaccinated, resume wearing masks indoors in places where the virus is surging. But many of those places have populations and politicians who are vehemently anti-mask. Some have even gone so far as to pass legislation banning mask mandates in schools, cities, and counties. Vaccination still remains the strongest protection against the delta variant, but the U.S. vaccination rate has stalled at just over 50 percent of eligible people 12 and older.