Federal health officials still believe fully vaccinated individuals represent a very small amount of transmission, the sources say. Still, some vaccinated people could carry higher levels of the virus than previously thought and potentially transmit the virus to others, they said.
The updated guidelines arrive ahead of the fall season, when the highly contagious delta variant is expected to cause a further rise in new coronavirus cases and many large employers plan to bring workers back to the office.
Read more: Americans will need masks indoors as US heads for ‘dangerous fall’ with increased cases of delta Covid
Health experts fear that delta, already the dominant form of the disease in the United States, could strike states with low vaccination rates and a high prevalence of the virus. These states are now forced to reintroduce rules on masks, capacity limits and other public health measures that they have largely reversed in recent months.
White’s chief medical adviser Dr Anthony Fauci said on Sunday that the CDC was considering revising the mask guidelines for vaccinated Americans, saying it was “under review.”
“It’s a dynamic situation. It’s a work in progress, it’s evolving like in so many other areas of the pandemic, ”Fauci, also director of the National Institute of Allergy and Infectious Diseases, told CNN. “You have to look at the data. “
The CDC’s advice is only a recommendation, leaving it to states and local authorities whether or not to reintroduce their masking rules for certain people. But even before the expected guidelines from the CDC on Tuesday, some regions were reintroducing warrants and mask notices.
Several counties in California and Nevada are now advising all residents to wear masks in indoor public places – whether or not they are vaccinated. In Massachusetts, Provincetown officials have advised all people to resume wearing masks indoors after the July 4 celebrations led to an outbreak of new cases.
Dr Paul Offit, a pediatrician and vaccine advocate who has served on advisory committees for the CDC and the Food and Drug Administration, told CNBC earlier this month that the United States is still “under-vaccinated,” with about half of the population not fully immunized.
Even fully protected people have reason to be concerned about the variants of Covid, Offit said. While vaccines protect well against serious illness and death, they may not protect as well against mild illness or the spread of Covid to others, he said. No vaccine is 100% effective, he noted.
“It is not a bold prediction to believe that SARS-CoV-2 is going to be circulating in two or three years. I mean there are 195 countries, most of which haven’t received a single dose of vaccine, ”Offit said. “Will it still circulate in the United States?” I think it would be very, very likely. “
Israel released preliminary data last week which showed Pfizer’s vaccine is only 39% effective against the virus there, which officials attributed to the rapidly spreading delta variant. Its effectiveness against serious illness and death has remained high, according to the data.
– CNBC’s Meg Tirrell and The Associated Press contributed to this report.
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