COVID Map Update: CDC Reveals States With ‘High’ Wastewater Viral Activity

Wastewater samples across several U.S. states have tested “very high” or “high” for levels of SARS-CoV-2—the virus that causes COVID-19.
Between November 3 and November 9, the U.S. Centers for Disease Control and Prevention (CDC) detected “very high” levels of COVID-19 in New Mexico, with “high” levels found in Montana, Wyoming and South Dakota.
“Moderate” levels were detected across Idaho, Nebraska, Maine, Nevada, Maryland, Rhode Island, Massachusetts, Michigan, Minnesota, and Missouri.
“Low” levels were found in 21 states, and “minimal” levels were detected in 14 states and D.C.
However, Arizona, Michigan, Mississippi, Missouri, New Hampshire, and South Dakota all have limited coverage, meaning that “data for the most recent week are based on a small part (less than 5 percent) of the population and may not represent viral activity levels for the entire state,” the CDC said. Additionally, North Dakota has no data for this period.
Between October 27 and November 2, wastewater sampling from New Mexico also had “very high” levels of the virus, but “high” levels were detected in Oregon, Arkansas, and Maine. The week prior, “very high” levels of viral activity were detected in Montana, with “high” levels in Arkansas, Maine, Minnesota, Nebraska, and Wyoming.
Infected individuals shed the virus in their feces, often before showing symptoms or even if asymptomatic. Therefore, monitoring wastewater virus levels allows authorities to detect the presence of COVID-19 early, even before clinical cases are reported.
“Wastewater (sewage) can be tested to detect traces of infectious diseases circulating in a community, even if people don’t have symptoms,” the CDC states. “You can use these data as an early warning that levels of infections may be increasing or decreasing in your community.”
Wastewater testing provides a snapshot of the overall infection levels in a community, regardless of individual testing rates, and is a way to monitor larger populations without needing to test each person.
However, the CDC notes that “states and territories may have a higher density of sampling sites in certain geographic areas, so the median wastewater viral activity level may not represent the wastewater viral activity level for every community in the state or territory.”
CDC data shows that national COVID wastewater levels have dropped massively since the summer months, approaching the low rates seen in April. However, last winter there was a huge spike in wastewater levels, so there could be a similar trend this winter.
Wastewater testing can also help health authorities detect variants of the virus circulating in the population, providing information about the potential emergence of new strains.
As of November 9, the predominant subvariant, KP.3.1.1 made up 39 percent of COVID-19 cases in U.S. wastewater over the previous two weeks, while the new XEC variant accounted for 20 percent, according to the CDC. KP.3 made up 17 percent, JN.1 made up 11 percent, and “other” made up 12 percent.
“There is no evidence, and no particular reason to believe, that XEC causes different symptoms than all the other SARS-CoV-2 currently in circulation,” Professor Francois Balloux, a computational systems biologist at University College London in England, previously told Newsweek. “XEC is not expected to cause more (or less) severe symptoms than other lineages currently in circulation.”
The CDC lists symptoms of COVID-19 as including:
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