CDC: Delta as contagious as chickenpox
The Centers for Disease Control and Prevention (CDC) say the Delta variant (B1617.2) is as contagious as chickenpox in an internal document leaked to the Washington Post today. The agency also said that, although vaccinated people rarely get serious breakthrough infections, when they do get infected they can transmit the virus as easily as unvaccinated people.
The document offers insight as to why CDC Director Rochelle Walensky, MD, MPH, earlier this week said vaccinated Americans should once again don masks when indoors in areas of high transmission—a category that 69.3% of US counties fall under, according to Reuters. High transmission is defined as 50 new daily cases per 100,000 people during a 7-day period.
In May, the CDC had said fully vaccinated people no longer needed to wear masks.
The CDC estimates there are now 35,000 symptomatic infections per week among 162 million vaccinated Americans, according to the document.
Massachusetts outbreaks shows high viral load in vaccinated
Much of the recent decision-making on mask use was based on data gleaned from a new report in Morbidity and Mortality Weekly Report, which detailed July 2021 outbreaks in Barnstable County, Massachusetts. Thousands of tourists traveled to the coastal Cape Cod towns in the county during the week following the Fourth of July.