US Community Highlights from the Sobering “Third Wave” of COVID

While the country may be experiencing its third wave, at a more local level, many communities are experiencing their first.

While COVID-19 continues to move through the Great Plains, Northern states, and expand through Wisconsin, we’re also finding new counties flicker on throughout the country, making the holiday season especially vulnerable to the spread of the virus. We have consistently found that smaller county clusters can expand to massive, difficult-to-contain state-wide megaclusters over the course of months if little is done to stop it.

What is especially striking is that the number of cases is similar to where we were at the end of July, nationally, but *where* the cases are this time, and how they emerged, are rather different.

We look especially at 7-day averages of confirmed total case numbers and population-adjusted figures to to understand the state of the virus. By normalizing counts to population, we can start to identify where communities that have been disproportionately impacted by the virus are.

Graphic by Dylan Halpern, with some concepts by Marynia Kolak.

Here’s a highlight of trends we’re finding of new cases across the country at the end of October:

• Megacluster of 7-day average new cases per 100,000 persons spanning North Dakota, South Dakota, much of Montana and Idaho, and spilling over into Northern Wyoming and Nebraska. This trend began as smaller, disconnected county hotspots at the end of August but grew gradually until connecting by mid-September, and from there exploding in early October to where we are now.

Multi-state megacluster of statistical hotspots (shown in red), as of Oct 26, 2020, using 7-day average of new cases per 100,000 people. (USAFacts data; theUSCovidAtlas.org made)

• Wyoming is clearly a place of emerging risk. In addition to some of the spillover from the Northern edge, there are spatial outliers emerging in the rest of the state showing elevated rates when compared to nearby counties. That means things can continue to exponentially grow without containment. Places like Converse and Platte counties have very low population numbers, but the proportion of cases is exceptionally high.
• Wisconsin continues to have multi-county hotspots of new cases, emerging mid-September to the entire Eastern side and now expanding further.
• The county of Doña Ana in New Mexico has flipped on as a statistical hotspot, using the 7-day case rate. Exponential growth is clear from the “new cases” graph since early September, so another area to focus on for containment.
• The borders between Eastern Arkansas and Western Tennessee have seen a lot of COVID-19 action, with persistent multi-county clusters on either side of the Mississippi River. As spillover persists and mitigation efforts can be challenged by varying state policy responses, it’s more important than ever to hone in and prevent infections from spreading further.

Cross-state spillover of statistical hotspots (shown in red), as of Oct 26, 2020, using 7-day average of new cases per 100,000 people. (USAFacts data; theUSCovidAtlas.org made)

• Western Kansas continues to see a multi-county cluster emerge with new cases, with some spillover into nearby Colorado and Nebraska.
• Additional clusters visible around Omaha, Iowa; multiple counties surrounding Jefferson City, Missouri; and western Texas around Hockley county.
• When switching over to 7-day case numbers, without population adjustment, several urban centers emerge, like Dallas, TX; Saint Paul, MN; Chicago, IL; Nashville, TN; surrounding counties of Charlotte, NC; Baltimore, MD; Philadelphia, PA; areas through NJ and NYC, and more.

We are also starting to see more cases in areas that have had very little COVID cases. For example, Wirth and Wetzel counties in West Virginia may be emerging spatial outliers, meaning they now have slightly elevated case rates when compared to nearby counties. Surrounding counties in this case have exceptionally low case rates. When a virus enters areas that were previously “coldspots” (ie. have few to no cases previously), the unfamiliarity with the virus and prevention measures necessary for containment can make the community especially vulnerable to worse outcomes.

Here’s what you can do:
- Wear a mask, especially when physical distancing is not possible. Encourage your friends and loved ones to do the same.
- Seriously consider alternate holiday plans.
- Avoid unnecessary exposure and travel.

Edits by Dylan Halpern, with additional feedback from COVID-Atlas team.