In light of the delta variant's continued spread and the rise of omicron, the Centers for Disease Control and Prevention encourages fully vaccinated people to mask up indoors if they live in a place with "substantial" or "high" coronavirus transmission.
The guidance for people who are unvaccinated is to always mask up indoors in public places.
So, what's the level of transmission where you live? Look up your county below.
The CDC classifies a community as having "substantial transmission" if there are 50 to 99 weekly cases per 100,000 residents or if the positivity rate is between 8.0 and 9.9% in the last seven days. (A high positivity rate indicates that the number of infections in a place may be high and that more testing is needed.)
If your county falls into this category, you should wear a mask indoors, whether or not you are vaccinated. The CDC also advises on its website that "everyday activities should be limited to reduce spread and protect the health care system."
The data for this map comes from the CDC. The color-coding is based on two metrics: the number of new cases per 100,000 residents and the percentage of coronavirus tests that come back positive in a seven-day period. If those two metrics show different levels of transmission in a given place, the CDC selects the higher level.
A county has "high transmission" if it has 100 or more weekly cases per 100,000 residents or a 10% or greater test positivity rate in the last seven days. In that case, communities should implement universal masking indoors and consider additional "significant measures ... to limit contact between persons," according to CDC's website.
Health experts say that the level of community transmission is not the only factor to guide whether you choose to wear a mask in public. There are other circumstances in which vaccinated people might want to mask up — for instance, if you live with unvaccinated children or have immunocompromised family members, or if you're going somewhere without good ventilation.
The CDC's director, Dr. Rochelle Walensky emphasizes the need for unvaccinated people to get vaccinated, noting that the areas with the lowest vaccination rates are getting hit hardest with infections. "With the delta variant," she said, "vaccinating more Americans now is more urgent than ever."