CNN —
New infections of the coronavirus disease (Covid-19) are no longer as closely tracked or reported as during public health emergencies. Instead, U.S. authorities are now focused on testing the contents of Americans’ wastewater to monitor for the virus.
To identify virus levels and larger trends, the U.S. Centers for Disease Control and Prevention relies on an extensive network of sampling sites at wastewater treatment facilities across the country. The surveillance network covers approximately 43% of the population.
This process does not accurately count the number of cases, and measurements can fluctuate based on sewage flow in a particular location or the characteristics of a particular variant at a given time. But this is an early warning about the spread of the virus, CDC officials say. CNN tracks these numbers weekly nationally and state-by-state, and this page will automatically update as CNN releases new information.
Virus levels vary over time and by location. This table shows trends by state, ranked in ascending order of severity of virus activity during the most recent testing period.
Samples are taken from sampling sites across the United States that meet standards to sufficiently anonymize data. Sampling allows CDC to see results from a large snapshot of the population, not just individuals participating in the health care system. Wastewater data can also help local public health agencies track new variants of the coronavirus and other infectious diseases such as RSV and MPOX.
The agency reports the rate of change in virus levels in each location where data is collected over a 15-day period, and some states with higher population density have more testing sites than others. This map shows their locations. Some sites saw an increase in activity, while others saw a decrease.
