What is wastewater surveillance?
Wastewater surveillance is one method used to monitor the amount of SARS-CoV-2 in an area. In Massachusetts, the Department of Public Health collects SARS-CoV-2 data from more than 20 Wastewater Treatment Plants (WWTPs).
How does wastewater surveillance work?
When a person has COVID-19, the SARS-CoV-2 virus is shed in their stool. A community’s collective wastewater flows to a wastewater treatment plant, where samples are taken and sent to a laboratory for SARS-CoV-2 testing.
What does wastewater surveillance data show?
Wastewater data can also help us track trends in the number of people that have COVID-19 in a community. The amount of virus that a person has in their stool and the length of time that they have virus in their stool varies. Because of this, the amount of virus measured in wastewater does not tell us total number of cases in the area and does not tell us the amount of increase or decrease in cases in communities. However, if the amount of virus in wastewater increases or decreases over several time points, that information shows that cases are either increasing or decreasing in the community. Importantly, wastewater data can provide an early warning about increasing cases since virus will show up in wastewater several days, maybe even a week, before positive test numbers start to increase.