The US Centers for Disease Control and Prevention said it will release a study Friday that supports this week’s decision to change mask guidance.
CDC Director Dr. Rochelle Walensky said Tuesday the agency was changing guidelines for fully vaccinated people because of new science.
She said even fully vaccinated people should wear masks indoors in areas where transmission of the virus is substantial or high.
Walensky said new data indicated that people who get breakthrough infections involving the Delta variant of the virus can be as likely to infect someone else as unvaccinated people are. And she promised that data would be released soon.