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Map: CDC indoor mask guidance applies to all Massachusetts counties

A sign at the Heaven Cafe encouraged customers to wear masks until seated in Provincetown on Saturday.Craig F. Walker/Globe Staff

Every county in Massachusetts now has “substantial” or “high” COVID-19 transmission rates, according to the Centers for Disease Control and Prevention, qualifying them for the agency’s indoor mask guidance.

The 14 counties mark an increase from five counties when the CDC first announced the new measure.

The CDC on July 27 announced an update to its mask-wearing guidance, suggesting that fully vaccinated people wear masks in indoor, public places in areas of the country with “substantial and high” transmission.

These are the counties where the guidance applies, according to data collected from Sept. 19 to Sept. 25:

High Transmission
  • Barnstable County
  • Berkshire County
  • Bristol County
  • Essex County
  • Franklin County
  • Hampden County
  • Hampshire County
  • Middlesex County
  • Plymouth County
  • Suffolk County
  • Worcester County
Substantial Transmission
  • Dukes County
  • Nantucket County
  • Norfolk County

This map shows where masks are recommended in Massachusetts based on data collected from Sept. 19 to Sept. 25:


According to the CDC, counties with 50-99 cases per 100,000 people or a test positivity rate of 8 to 9.9 percent over the previous seven-day period are considered to be experiencing “substantial transmission,” and counties with 100 or more cases per 100,000 people or a test positivity rate of 10 percent or higher over the the past 7 days are considered “high transmission.”

During the announcement, CDC chief Dr. Rochelle Walensky noted there are counties in the country with concerning amounts of COVID-19 transmission.

“We have places and counties and states here that are now reporting over 300 cases per 100,000 over a seven-day period so really an extraordinary amount of viral transmission, which is what we’re concerned about,” Walensky said.

A map of COVID-19 transmission in the United States showed large swaths of the country classified as “high transmission” areas. Some states, like Missouri, Arkansas, Mississippi, and Alabama had almost every county classified as “high transmission,” and therefore subject to the new CDC mask guidance.

Correction: An earlier version of this story misidentified the county with “moderate” transmission levels. The county is Hampshire county.


Amanda Kaufman can be reached at Follow her @amandakauf1.