Sewage shows we’re undercounting coronavirus cases – by a lot, MA researchers say

Sewage at a major treatment facility in Massachusetts showed there are likely hundreds more people with coronavirus in the area than officials thought, researchers say.

Biobot Analytics, along with researchers from MIT, Harvard and Brigham and Women’s Hospital, tested samples of wastewater from an urban treatment plant in March, according to a report posted to the preprint server medRvix. Researchers found the amount of coronavirus particles in the samples was far higher than expected, indicating there are likely a lot more people infected with the virus than the official count, Newsweek reported.

Coronavirus can be found in human feces, according to the Centers for Disease Control and Prevention. Researchers with Biobiot Analytics find COVID-19 in sewage by looking for its genetic fingerprint, the report on medRvix said.

There were about 450 confirmed coronavirus cases in the area of the treatment facility, but researchers estimated that the number of people actually infected with coronavirus is between 2,300 and 115,000, Newsweek reported. But Eric Alm, one of the study’s authors, emphasized that while they can detect the virus in urine and feces, people are not at risk of getting the disease through sewage, Newsweek reported.

The results of Biobot Analytics’ research are consistent with other studies in the Netherlands and Sweden, where COVID-19 was also found in several treatment plants, according to the science journal Nature. But before researchers can precisely quantify the scale of infection in a population, they have to figure out how much RNA from the virus is shed from the body in feces, Nature reported.

Studies also need to be conducted over a longer period of time, since current research only shows a “snapshot in time,” Nature said.

“Studies have also shown that SARS-CoV-2 can appear in [feces] within three days of infection, which is much sooner than the time taken for people to develop symptoms severe enough for them to seek hospital care,” Tamar Kohn, an environment virologist at the Swiss Federal Institute of Technology told Nature.

Using sewage to detect viruses is not a new method.

“Wastewater monitoring has been used for decades to assess the success of vaccination campaigns against poliovirus,” Charles Gerba, an environmental microbiologist at the University of Arizona, told Nature. Gerba also found traces of coronavirus in raw sewage in Tucson, Arizona, according to Nature.

This story was originally published April 9, 2020 at 10:53 PM.