Walsh Announces City Will Publicize New COVID Metrics

Mayor Martin Walsh and his administration announced on November 17 that they would be releasing more COVID-19 metrics to the public moving forward, as well as adjusting the metric on positivity rate.

Walsh said that in Boston as of Monday, there were 239 new cases reported and four deaths since Friday.

¡°We¡¯re going to continue to monitor the data that we have,” said  Chief of Health and Human Services Marty Martinez, but data will now be released to the public twice a week using six metrics.

The metrics include new positive tests for COVID-19 in Boston residents, which Martinez told reporters on Tuesday “tells us how many new cases we’re seeing each day and how quickly COVID-19 is spreading in Boston.” Each of these metrics comes with a threshold of concern as well, and in this case it would be 339.6 cases per day or 50 cases per 100,000 residents per fay.

Another metric is positivity for COVID-19 in Boston residents, which shows the percentage of tests that are returning positive out of all those who are tested in a specific period of time. Martinez explained that a high positivity could indicate widespread infection in a particular community and/or “only a subset of the community at greatest risk for COVID infection is being tested.”  In this case, the threshold of concern would be a positivity rate of 5 percent or higher or four or more Boston neighborhood rates above eight percent.

“Up to now, Boston has used a person-level approach using a cumulative time frame that looks back to the beginning of the epidemic,” the presentation said, “meaning each person is only counted once, even if they have been tested repeatedly.”

Moving forward, a hybrid model will be used that includes person-level and test-level positivity, and will not include college testing, though that will continue to be monitored separately, he said. He said the reason for this is to get a better look at positivity at the neighborhood level without college data skewing it.

“We think it more accurately depicts recent positivity due to a tighter time frame for testing,” and “provides a more accurate depiction of unique new positives,” Martinez said.

He said for those people who get tested multiple times a week, only one negative test will be counted, but any positive results get counted once every 90 days to prevent repeated reporting of the same positive test. Martinez said that the current positivity rate in Boston as of November 12 using this metric is 5.4%, and

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