Real-time coronavirus surveillance from 700+ CDC monitoring sites across the US
View Live COVID-19 MapClinical COVID-19 case counts depend entirely on who gets tested — and since home tests became widely available, most positive results are never reported to health departments. Hospital admission data lags by weeks. Wastewater surveillance sidesteps these problems entirely: it measures viral shedding from the whole community, regardless of whether anyone buys a test, visits a doctor, or reports their result.
This makes wastewater the most complete, unbiased measure of true COVID-19 community prevalence available today. The CDC has relied on NWSS wastewater data as a primary COVID signal since 2021.
SARS-CoV-2 (the virus that causes COVID-19) is shed in the feces of infected individuals — including those who are asymptomatic. Viral shedding begins before symptoms appear and continues for several days after recovery. This means wastewater signals often rise 4–7 days before clinical indicators, giving hospitals and public health agencies critical lead time.
Each monitoring site on Outbreak Radar represents a wastewater treatment plant that samples influent, extracts viral RNA, and measures SARS-CoV-2 concentration using PCR. The CDC normalizes these readings using PMMoV to enable cross-site comparison. See our How It Works page for full methodology details.
As new SARS-CoV-2 variants emerge, wastewater surveillance often detects their spread before genomic sequencing data becomes available at the national level. Some advanced NWSS sites perform genomic sequencing of wastewater samples to identify which variants are circulating — providing early warning of variant emergence or displacement.
Outbreak Radar currently tracks overall COVID-19 wastewater concentration. When variant-specific wastewater data becomes widely available through the NWSS, we plan to incorporate it.
Blue dots on the Outbreak Radar map represent COVID-19 monitoring sites. Dot size reflects the current week's concentration as a percentile of that site's own full history of active (non-zero) readings:
COVID-19 in the US tends to follow a bimodal pattern — a winter surge (December–February) and a summer surge (July–August) — though this pattern has become less predictable as population immunity has evolved.
COVID-19 symptoms vary widely by variant and vaccination status. Common symptoms include fever, cough, fatigue, sore throat, runny nose, muscle aches, headache, and loss of taste or smell (less common with recent variants). Many infections are now mild, especially in vaccinated individuals. For current symptom guidance, see the CDC COVID-19 symptoms page.
Updated COVID-19 vaccines are reformulated annually to target current variants. The CDC recommends that everyone 6 months and older stay up to date with COVID-19 vaccination. Antiviral treatments (Paxlovid, Lagevrio) are available by prescription and most effective when started within 5 days of symptom onset — check current eligibility with your healthcare provider.
Data comes from the CDC NWSS, updated weekly. COVID-19 has the longest wastewater surveillance history of any pathogen on this site, with data going back to mid-2022 at most monitored sites.