Illinois State Water Survey researchers have taken a unique approach to look for traces of SARS-CoV2, the virus that causes COVID-19, at the neighborhood level in Champaign-Urbana to help monitor the spread of infection.
In early January 2021, ISWS field technicians Kip Stevenson and Hayden Wennerdahl deployed automatic pump samplers to collect sewer water as part of a project led by Thanh H.(Helen) Nguyen, professor in the U of I Civil Environmental Engineering (CEE) Department. The technicians used high-resolution composite sampling in various neighborhoods as opposed to the grab sampling protocols being conducted at the wastewater treatment plants in the Chicago area and other big cities.
A grab sample is taken just once and shows a snapshot of the outcome only at the time when it is collected. High-resolution sampling, however, is crucial to determine pockets of the population where infection is more prevalent. This type of sampling can be done at places where frequent human testing is not available.
In addition, previous work on sewage monitoring has shown that high-resolution sampling can provide an indication of infection a few days before other types of COVID tests return positive results, which could provide an important early warning tool. This information will assist the decision-making processes at the city and county level, as it is necessary to know whether infection spread is continuing within a community.
Once the four samplers were installed inside manholes, samples are collected every four hours, day and night. A composite of each sample is combined, and Wennerdahl retrieves the final sample each Monday. CEE researchers analyze the results.
SARS-CoV2 was detected in Champaign-Urbana throughout the spring. Samplers were placed in Campustown, in a low-income neighborhood in Champaign and one in Urbana, and in a long-term stable neighborhood in Champaign.
Samples collected in late April 2021 all tested positive for the presence of SARS-CoV2. Between January and April in Champaign-Urbana, Campustown had the highest detection frequency of the virus, followed by a low-income neighborhood in Urbana. Samples collected in May showed the potential presence of the SARS-CoV2 UK variant in a neighborhood outside of Campustown.
This project will continue through the summer so scientists can better understand how vaccinations, travel, and resuming normalcy in daily life influence the level of COVID-19 infection and distribution of variants in the community.
