Why wastewater catches what testing misses
People shed SARS-CoV-2, influenza, and RSV in stool whether or not they test, whether or not they have symptoms, and whether or not they ever see a doctor. A treatment plant samples everyone in its service area at once, so the signal does not depend on who decides to get tested. When home testing replaced lab testing, case counts stopped tracking reality. Wastewater kept working.
How the state numbers are built
CDC publishes a Wastewater Viral Activity Level for each individual treatment site, but its state and national figures are not available as a downloadable dataset, so this page recomputes them from the site data using CDC's own published method. A state is the median of its sites, each region is the median of its states, and the national number is the median of the four regions. That same method runs for all three tracked pathogens. The category cut points are CDC's own, and each pathogen has its own set: CDC says plainly that each virus behaves differently, so SARS-CoV-2, influenza A, and RSV are each scored against their own published thresholds rather than sharing one scale, applied as written and not rescored here. [R]
Checked against CDC's own numbers
Because both the method and the category cut points are CDC's, this page reproduces CDC's published figures rather than approximating them. For SARS-CoV-2, checked against the feed behind CDC's own state dashboard for the week ending August 1, 2026: all 52 reporting jurisdictions matched exactly, on both the number and the category, as did the national figure. One presentational difference: CDC lists North Dakota as Limited/No Data, while this page leaves it unshaded, because no North Dakota site reported. Influenza A and RSV run through the identical code path and CDC's own published thresholds for each, but have not been separately spot-checked against CDC's dashboard the same way. CDC's dashboard remains the authority.
Reading the trend arrows
A state is marked rising or falling only when it moves more than 5% against the prior week. Anything smaller shows as steady. Wastewater is noisy week to week, and without that deadband nearly every state would show an arrow every week.
How the Long COVID layer is measured
The Long COVID view has two sources. The latest national estimate comes from the National Health Interview Survey (3.6% of US adults currently experiencing Long COVID in 2024). The state map uses the final Household Pulse Survey (Sept 2024), still the most recent state-level data available; CDC's next state update, from the 2024 BRFSS, is anticipated December 31, 2026. Both are population surveys, not live case counters. Every reading keeps its collection period and 95% confidence interval attached, and states that CDC suppresses for statistical reliability remain visibly unscored rather than being filled from an older period. The map shading is relative to the highest published state estimate in that same survey period; it is not a clinical severity threshold. [R]
What this cannot tell you
The most recent week is preliminary and shifts as more sites report, so treat the newest point as a draft. Coverage is uneven: some states have dozens of reporting sites and others have a handful, and North Dakota currently reports none. Wastewater shows how much virus is circulating in an area. It cannot tell you your personal risk, and it is not a diagnosis.