CDC Director Dr. Rochelle Walensky said new data shows the delta variant, which accounts for more than 80% of the new infections in the U.S., behaves "uniquely differently'' from its predecessors and could make vaccinated people infectious.
"Information on the delta variant from several states and other countries indicates that in rare occasions some vaccinated people infected with the delta variant after vaccination may be contagious and spread the virus to others,''
Earlier in the day, White House press secretary Jen Psaki said the CDC, which in May said vaccinated Americans no longer needed to mask up in public, has been forced to reassess because of the emergence of the highly infectious delta variant.
The delta variant has ripped through unvaccinated communities in the U.S., accounting for almost all recent hospitalizations and deaths. Public health officials have said vaccines largely protect vaccinated individuals from severe disease and death, but breakthrough cases are possible