The Recorder – Contact Tracing Collaborative Creates Alert System to Monitor COVID-19 Risk Levels

GREENFIELD — The Contact Tracing Collaborative has created a traffic light alert system, outlining low, moderate and high risk thresholds for COVID-19 transmission in an effort to illustrate case levels and provide residents with tips for masking.

The four-city collaboration includes Greenfield, Deerfield, Sunderland and Montague and is funded by grants.

The idea, said Greenfield Health director Jennifer Hoffman, is to give people the information they need if they’re attending a concert, party or other large gathering. Masking is recommended in red zone (high risk), encouraged in yellow (moderate risk) and optional in green (low risk).

The collaboration is currently in the red zone, Hoffman said Friday afternoon, after receiving Greenfield’s sewage analysis report, which reflected sewage samples taken Oct. 5. The report shows a volume of 3.6 million virus copies per liter of wastewater (a value which is adjusted from the raw value to reflect dilution and other factors), compared to 2.7 million copies per liter of wastewater from the previous week.

The report also says Greenfield has a higher virus concentration than 98% of Massachusetts communities testing sewage.

Although the traffic light system takes into account various factors, Hoffman explained that with fewer people seeking PCR tests and non-state reportable home tests, local public health officials are beginning to relying more on sewage testing to inform residents of changing levels of COVID-19 in their communities. Every week, sewage samples are sent to Cambridge-based BioBot Analytics and tested for COVID-19. All four member cities involved in the collaboration participate in the program.

“(The sewage) is a really good early indicator if there are people with COVID in our area,” Hoffman said. “Everyone uses the bathroom and as long as they have a public sewer we are able to tell…if COVID is in the sewage.”

She added that higher levels of viruses found in sewage often go “hand in hand” with increased hospitalizations.

In combination with sewage testing, the four communities consider the number of hospitalizations, positivity rates and case counts when using the traffic light alert system. Public health officials also continue to communicate with nursing homes, businesses and schools to track infections in clusters, or more than three people at one site. For the level of risk in the area to increase, at least two measures must apply.

“The collaboration…decided to work together, mainly because a lot of residents are going back and forth to all of these cities,” Hoffman explained. “We really put a lot of time into it, and that’s what we found.”

She added that public health officials continue to receive questions from residents who are concerned about levels of COVID-19 in their community.

“We allow people to plan their week,” she said, “based on what we know.”

Journalist Mary Byrne can be reached at [email protected] or 413-930-4429. Twitter: @MaryEByrne.

Red zone: high risk of COVID-19

Masking recommended

■ Cluster infections (of three or more people at one site): five or more

■ Percentage of positive tests out of the total number of tests carried out: greater than 10%

■Hospitalizations: five or more

■Increase in the trend of cases

■ Increased sewage trend

Yellow zone: Moderate risk of COVID-19

Masking encouraged

■One to four cluster infections

■Stable positive test

■Less than five hospitalizations

■ Stable case incidence

Green zone: low to minimal risk of COVID-19

Masking optional

■No cluster infection

■ Decrease in positive tests

■ Fewer hospitalizations

■ Decrease in incidence of cases

■ Decrease in virus copies in wastewater