The Centers for Disease Control and Prevention (CDC) warned Congressional lawmakers earlier this week that the Delta variant has a longer transmission window that the original strain of the virus and is as contagious as chickenpox. The CDC also cautioned that the strain is infecting even fully vaccinated people.
The warning was made in a confidential document that has been reviewed by multiple news outlets, including the New York Times and the Washington Post, with the latter publishing the document on its website.
The CDC report showed that the variant is more likely to break through the immunity protections afforded by vaccines developed by Pfizer
The CDC report found the Delta variant to be highly contagious, with data supporting theories that breakthrough infections among the fully vaccinated may be as transmissible as those among unvaccinated populations. However, CDC data shows that the vaccines are still highly effective in preventing severe illness, hospitalization and death.
In comparing the mutant strain's transmissibility, the CDC found that Delta is more contagious than the original strain of SARS-CoV-2 as well as the viruses behind MERS, SARS, Ebola, the common cold, the seasonal flu and smallpox. The CDC data supports that Delta is as contagious as chicken pox, with only the measles virus appearing to spread faster.
However, the variant was found to be only as deadly as the original COVID strain.
The CDC's findings corresponded with an agency study published Friday in the agency's Morbidity and Mortality Weekly Report which found that about 75% of people infected in a COVID-19 outbreak in Massachusetts were fully vaccinated against the virus. This study demonstrated that fully vaccinated people can not only get infected, but carry as much of the virus in their nose and throat as unvaccinated people, and could further spread the virus to others.
"This finding is concerning and was a pivotal discovery leading to CDC's updated mask recommendation," CDC Director Dr. Rochelle Walensky said in a statement, referring to the agency's decision on Tuesday to recommend fully vaccinated people wear masks again indoors in areas of high infection rates. "The masking recommendation was updated to ensure the vaccinated public would not unknowingly transmit virus to others."
The CDC noted in the Thursday report that its next step to combat the coronavirus pandemic is to improve the public's understanding of breakthrough infections and encourage those who are unvaccinated to get a shot as it decreases their risk of severe disease.
