To prevent further spread of the Delta variant, the US Centres for Disease Control and Prevention updated its mask guidance on Tuesday to recommend that fully vaccinated people wear masks indoors when in areas with “substantial” and “high” transmission of Covid-19, which includes nearly two-thirds of all US counties.
“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,” CDC Director Dr Rochelle Walensky told a media briefing on Tuesday.
“This new science is worrisome and unfortunately warrants an update to our recommendations,” she said. “This is not a decision that we or CDC has made lightly.”
New unpublished data showing that vaccinated people infected with the Delta coronavirus variant can have as much virus as those who are unvaccinated is the primary driver for the CDC’s latest mask guidance change, a source involved with the decision process told CNN. Overall, vaccinated people still play a small role in transmission and breakthrough infections are rare.
In addition, the source noted two other factors that led to this decision: the prevalence of the Delta variant and low vaccine uptake.
When the CDC previously revised its guidance on May 13 for vaccinated people to unmask, Delta only represented 1% of reported infections. Now, according to the CDC, it represents at least 83% of cases.
The source also noted that the country’s overall level of vaccination is lower than what was initially expected and that most transmission is happening in areas with vaccination levels below 40% of the population.
“When you get information about risks and how to mitigate risks, there’s a public health obligation to let people know about it,” a senior administration official said. The White House is hoping that the new guidance will give local officials “a lot of cover” to implement new mask mandates where appropriate.
Meanwhile, the guidance for unvaccinated people remains the same: continue masking until they are fully vaccinated. (CNN)
