As we predicted yesterday (and updated hours after publication), the CDC has revised its guidance from last May — which said that vaccinated people do not need to wear masks in most indoor settings. Now the recommendation is that everyone mask up indoors in places where Covid-19 transmission is “high” or “substantial.” The agency made this change because of emerging evidence that vaccinated people can become infected and harbor high levels of virus in the upper airway, and possibly transmit it onward.

In Minnesota, at this writing 14 counties (out of 87) fall under these guidelines. That’s 16% of the counties numerically, so on that basis this state is doing well compared to the US as a whole. For the country, about 66% of counties fall under the CDC’s new guidance. Here are the Minnesota counties:

Cottonwood
Dodge
Isanti
Lake
Lake of the Woods
Mille Lacs
Pope
Redwood
Roseau
Scott
Swift
Traverse
Waseca
Wilkin

They are shown in orange or red on this map, taken from the CDC’s Covid Data Tracker website. (Yellow represents “moderate” spread and blue is “low.”)

These counties represent 6.4% of the state’s population, using 2010 census numbers.

I will be exploring ways to update this post as the virus’s spread changes over the upcoming weeks.