Editor’s note: The Greenfield Recorder plans to provide regular updates on the risk level of COVID-19 transmission as wastewater testing results are received.
GREENFIELD — The Contact Tracing Collaborative has created a traffic light alert system, outlining thresholds for low, moderate and high risk of COVID-19 transmission in an effort to illustrate case levels and provide residents with guidance for masking.
The four-town collaborative includes Greenfield, Deerfield, Sunderland and Montague and is grant-funded.
The idea, said Greenfield Health Director Jennifer Hoffman, is to provide people with the information they need if they’re attending a concert, party or other large gathering. Masking is recommended when in the red zone (high risk), encouraged in yellow (moderate risk) and optional in green (low risk).
The collaborative is currently in the red zone, Hoffman said Friday afternoon, following receipt of Greenfield’s wastewater testing report, which reflected sewage samples collected on Oct. 5. The report shows a volume of 3.6 million copies of virus per liter of sewage (a value that is adjusted from the raw value to reflect dilution and other factors), compared to the previous week’s 2.7 million copies per liter of sewage.
The report also indicates Greenfield has a virus concentration higher than 98% of Massachusetts communities testing wastewater.
Although the traffic light system considers a variety of factors, Hoffman explained that with fewer people seeking PCR tests and at-home tests not reportable to the state, local public health officials are beginning to rely more on wastewater testing to inform residents of changing levels of COVID-19 in their communities. Each week, wastewater samples are sent to the Cambridge-based BioBot Analytics and tested for COVID-19. All four member towns involved in the collaborative are participants in the program.
“(Wastewater) is a very good early indicator if there are people with COVID in our area,” Hoffman said. “Everyone uses the bathroom and as long as they have public sewer, we’re able to know … if COVID is in the wastewater.”
She added that higher levels of virus being found in the wastewater often goes “hand-in-hand” with increases in hospitalizations.
In combination with wastewater testing, the four communities are factoring in hospitalization numbers, positivity rates and case numbers when using the traffic light alert system. Public health officials also continue to communicate with nursing homes, businesses and schools to track cluster infections, or more than three people at one site. For the risk level in the area to rise, at least two measures need to apply.
“The collaborative … decided to work together, mostly because a lot of the residents go back and forth to all these towns,” Hoffman explained. “We really put a lot of time into this, and this is what we came up with.”
She added that public health officials continue to get questions from residents who are concerned about COVID-19 levels in their community.
“We’re allowing people to plan their week,” she said, “based on what we know.”
Reporter Mary Byrne can be reached at mbyrne@recorder.com or 413-930-4429. Twitter: @MaryEByrne.
Red Zone: High COVID-19 Risk
Masking recommended
■Cluster infections (of three or more people at one site): five or more
■Percent positive tests out of total tests performed: greater than 10%
■Hospitalizations: five or more
■Increase in case trend
■ Increases in wastewater trend
Masking encouraged
■One to four cluster infections
■Stable positive testing
■Fewer than five hospitalizations
■Stable case incidence
Masking optional
■No cluster infections
■ Decrease in positive tests
■ Decrease in hospitalizations
■Decrease in case incidence
■Decreased virus copies in wastewater