The spread of the Delta variant of the coronavirus has launched a new phase of the pandemic in the United States.
Across the country, COVID-19 cases are rising both among the vaccinated and the unvaccinated. This week, the Centers for Disease Control and Prevention updated its guidance about masking. The organization has long recommended that unvaccinated people wear masks indoors, but as of Tuesday, it’s advising vaccinated people to mask up indoors in some high-risk areas. This latest guidance is a result of new CDC research that finds that while it’s rare for vaccinated people to get infected with the coronavirus and spread it to others, so-called breakthrough cases do happen. And crucially, Dr. Rochelle P. Walensky, the director of the agency, says that when the vaccinated do get infected with the Delta variant, they carry just as much virus in the nose and throat as unvaccinated people, which means they are just as likely to spread it to others.
Since the rate of spread varies so much from day to day, and from region to region, this guidance presents new challenges for vaccinated people. If you had grown used to the freedom of not wearing a mask, you now need to do research about the latest COVID-19 numbers in your area, then determine whether it’s time to dig out your masks and keep them handy whenever you’re in an enclosed public space.
Fortunately, NPR has created a useful map that’s regularly updated with CDC data about the rate of spread at a county level. The map is color-coded to identify areas of low, moderate, substantial, and high spread. To calculate the rate of transmission, the CDC identifies the number of new cases per 100,000 residents, as well as the percentage of COVID-19 tests that came back positive in the previous seven days.
If you live in a county in a red zone on the map, where rates of spread are substantial or high, the CDC recommends you wear a mask indoors, whether or not you’ve been fully vaccinated. But public health experts point out that even in places with low to moderate spread, there might be reasons to continue masking. For instance, if you live with immunocompromised people or children who are too young to be vaccinated, it would be wise to take extra precautions to avoid bringing the virus home.
As of right now, roughly two-thirds of U.S. counties are experiencing substantial or high transmission rates. In at least three states—Florida, Louisiana, and Arkansas—every single county has high or substantial community spread of the virus, so the CDC recommends everyone wears a mask.
According to analysis by PHICOR, a public health research group, areas with low rates of vaccination are now seeing higher rates of coronavirus transmission. Counties in southern Missouri and northern Arkansas, where vaccination rates are low, are experiencing large COVID-19 outbreaks. Researchers caution that even in places where vaccination rates are as high as 70% or 80%, there might still be pockets of vulnerability.