While nationwide COVID-19 cases have dwindled in recent weeks, wastewater detections of the virus still remain "very high" in certain states.

Newsweek have revealed this variability in a map based on data from the U.S. Centers for Disease Control and Prevention (CDC).

As of October 5, the overall viral activity level in wastewater across the country has been demoted from "moderate" to "low," although "very high" levels are still being detected in two states. A further 14 states have "high" wastewater detection levels, with seven detecting "moderate" levels and 15 classified as "low."

Eight states, including D.C., are now reporting "minimal" detection levels, the lowest classification in the CDC's system.

After a surge in COVID cases this summer, infection rates seem to be on the decline. As of October 5, positive results account for only 7.7 percent of all tests (excluding at-home testing) in the U.S., down 0.8 percent from the previous week. However, coronavirus levels do remain high in certain states, especially in the Northwest.

The map below shows which states have seen the highest detections in wastewater.

Viral levels in wastewater are a helpful indicator of disease prevalence within a population.

Recent spikes in COVID cases have been largely driven by a new class of subvariants nicknamed FLiRT after the position of the mutations on the virus' spike proteins, the projections that allow them to enter our cells.

These proteins are also used as targets by immune systems and vaccinations, so changes in their structure can allow the virus to bypass the body's defenses more easily. However, existing vaccines are likely to provide at least some form of protection against more severe symptoms and long COVID.

As of October 12, the now dominant subvariant, KP.3.1.1, accounted for more than 57 percent of all U.S. COVID-19 cases over the previous two weeks, according to the CDC, with the FLiRT variants accounting for more than two thirds of cases in total.

However, while the U.S.saw a steady rise in infections over the summer, hospitalizations and deaths have remained relatively low. It appears that the new FLiRT variants, while more infectious, do not generally cause such severe symptoms.

The symptoms include the following, according to the CDC:

  • Fever or chills
  • Cough
  • Shortness of breath
  • Fatigue
  • Muscle or body aches
  • Headache
  • Loss of taste or smell
  • Sore throat
  • Runny nose
  • Nausea or vomiting
  • Diarrhea

More vulnerable individuals may still be at risk of severe illness, so it is important to self-isolate if you receive a positive COVID test.

Coronavirus wastewater map as of October 5. COVID cases remain relatively high in some states, particularly in the Northwest. Coronavirus wastewater map as of October 5. COVID cases remain relatively high in some states, particularly in the Northwest. Chanakarn Phinakan / iStock / Getty Images Plus

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