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Six things everyone should know about yesterday’s CDC guidance on masks and COVID-19

The Centers for Disease Control and Prevention announced new guidance around COVID-19 transmission and masking on Tuesday.Matthew J. Lee/Globe staff

The Centers for Disease Control and Prevention on Tuesday revised its guidance on masking and COVID-19 transmission, recommending that some fully vaccinated people return to wearing masks indoors as the Delta variant spreads across the country.

Here’s what we learned from the announcement.

Wear a mask again in parts of the United States

Even vaccinated people should wear masks in indoor public spaces in parts of the country, the CDC advised. The guidance applies to areas with at least 50 new cases per 100,000 people in the last week. That currently includes 60 percent of US counties, officials said.

Five counties in Massachusetts fit that category


Five Massachusetts counties are considered to have “substantial and high transmission”: Suffolk (Boston, Chelsea, Revere, and Winthrop), Bristol (areas around Fall River, New Bedford, Taunton, and Attleboro), Barnstable (Cape Cod communities such as Provincetown, Falmouth, Sandwich, Dennis), Nantucket, and Dukes (mostly Martha’s Vineyard).

Masks should be required in schools

Regardless of vaccination status, students, teachers, staff, and visitors should wear masks in K-12 schools this fall, the CDC recommended.

Vaccinated people can spread COVID-19

Most new infections occur in unvaccinated people. Still, vaccinated people “have the potential to spread that virus to others,” Dr. Rochelle Walensky, said the CDC’s director.

The viral load with the Delta variant is higher

Vaccinated people infected with the Delta variant have a level of virus that is “indistinguishable” from that in the noses and throats of unvaccinated people, Walensky said. That finding comes from unpublished data that emerged over the past few days from more than 100 samples in several states and one other country.

With earlier strains of the virus, infected vaccinated people had low levels of virus and were not considered likely to spread the virus too much, Walensky said.

Masking to protect vulnerable folks

The CDC recommended that fully vaccinated people mask up regardless of transmission levels in their community if they are immunocompromised or at increased risk for severe disease from COVID-19, or if someone in their household is.


The same guidance applies if someone in their household is unvaccinated, including children under 12 who are not yet eligible.

What questions do you still have about the new CDC guidance? Tell us below:

Sahar Fatima can be reached at sahar.fatima@globe.com Follow her on Twitter @sahar_fatima.