Red municipalities plummet with changed metrics
Number falls from 121 last week to 16 this week
WITH THE NUMBER of Massachusetts communities considered high-risk for COVID-19 growing at an alarming rate, the Baker administration on Friday changed the metrics it uses to set risk levels and cut the number of municipalities designated as red by 87 percent.
The administration had been using a one-size-fits-all system for determining whether a community was low (gray and green), moderate (green), or high (red) risk based on the average number of cases per 100,000 people over the previous two weeks.
On Friday a new system was rolled out that lumps communities into three different groups based on population size and then measures risk for each group using different metrics – the number of overall cases in smaller communities and a combination of cases per 100,000 and the positive test rate (positive cases divided by total tests) in the larger ones. Even the cutoff for the red, or high-risk, designation was raised from 8 to 10 cases per 100,000 people.
Using the new metrics, the number of red communities plummeted, falling from 121 a week ago to 16 on Friday. The number of moderate risk yellow communities increased from 76 to 91 and the number of low-risk gray and green communities jumped from 197 to 244.
The 16 communities in the red zone included Lawrence (62.4 cases per 100,000), Norfolk (48 cases), Chelsea (45.1), Revere (44.3), Fall River (41.8), Fitchburg (39.2), Everett (36), Somerset (35.9), Westport (35), and Lynn (34.4). The other six, all with case counts in the 20s, were Seekonk, New Bedford, Lowell, Methuen, Springfield, and Brockton.
Many other communities would have been designated red but for the new, added metric of positive test rate. Nantucket has been a fixture on the high-risk list. On Friday, however, Nantucket reported 25 cases per 100,000 people, up from 12 last week, but its positive test rate was 3.18 percent, below the 5 percent cutoff for a community its size.
Holyoke followed the same pattern. Holyoke reported 30.9 cases per 100,000 people, but its positive test rate was 4.76 percent.
The change in metrics could have broad implications for affected communities. The Baker administration is encouraging any non-red community to resume in-person schooling and even encouraging red communities to consider iin-person schooling if the spread of COVID-19 is not occurring in schools. A community’s color-coded designation also affects a municipality’s ability to reopen businesses.
Differentiating communities by size makes sense because minor outbreaks of COVID-19 in smaller communities can drive them into the red zone just because the population base is so small.
Adding a second metric – the positive test rate – is more controversial because the state is testing for COVID-19 so aggressively. The positive test rate is calculated by dividing the number of positive cases by the number of tests. Doing more tests tends to drive down the positive test rate, reducing the number of communities that qualify as high risk.
Winthrop, which has been a fixture on the high-risk list in past weeks, had a very high 55.3 cases per 100,000 people over the last two weeks, but its positive test rate (186 positive tests divided by total tests of 4,619) was 4.03 percent, nearly a point below the 5 percent threshold for a community its size.
“I want people to test. I want to incentivize people to test,” Baker said. “I happen to think that this is a more nuanced and accurate way to test how communities are doing.”