The US Centers for Disease Control and Prevention is expected to update it guidelines on Tuesday to urge vaccinated people in certain areas of the country to resume wearing masks because of Covid-19.
A senior administration official said the decision was spurred by the more transmissible Delta variant.
"It's based on the fact that the Delta variant is clearly more transmissible than the prior ones,” the official said.
A health official says, based on the latest data, officials believe vaccinated people only represent a small amount of coronavirus transmission and the overwhelming majority of spread is still by unvaccinated people. But they know breakthrough cases can happen and emerging data suggests some vaccinated people can spread it, which is the driving factor behind Tuesday’s decision, as they continue to study it.
CDC Director Dr. Rochelle Walensky is expected to explain the decision at the 3 p.m. Tuesday briefing, the official said.