This is a follow-up to the first post documenting how the coronavirus has differentially impacted communities in Massachusetts, using the state’s weekly public health report for data. That post https://www.masscoronavirus.net/community-spread-in-massachusetts-september-26-2020/ described some of the issues with the weekly report, as well as my methodology for calculating how a particular city and town has contributed to the change in either case incident rates or test positivity rates in the state.
|Table 1: Highest Case Incident Rates and Contribution to Case Incidence Increase|
|Period Ending October 17, 2020|
|Highest Case Incident Rates||Largest Contributors to Weekly Case Incidence Increase|
|City/Town||14 Day Case Count||Daily Case Rate per 100,000||City/Town||14 Day Case Count||Daily Case Rate per 100,000||% Contribution|
The three left hand columns focus on the communities with the highest per capita case incident rates for the two-week period ending October 17. The state did make one change to the report, adding an asterisk to communities to indicate where some of the cases are institutional and not directly attributable to the local community. A municipality has an asterisk if it has a long-term care facility, a higher-education facility, or a correctional facility that (1) has had more than ten cases in the past fourteen days, and (2) these cases are more than 30% of cases in the community over the past fourteen days. In the case of Middleton, at the top of the list, Middleton House of Corrections has had a large covid outbreak.
The four right hand columns focus on the communities which contributed the most to the increase in the statewide case incidence rate. As I discussed in the prior post, communities on this list tend to be either large in population (e.g., Boston, which is on the list because of its size), or have had a very large change in case incidence (e.g., Gloucester and Saugus, both with populations of abut 30,000). Boston’s case incidence rate increased by about 8%, but Gloucester’s rate almost tripled. The case incidence rate increased statewide from 8.7 cases to 9.2 cases per 100,000 population per day.
The last column in Table 1 shows the percentage contribution of each community to the statewide increase. This column emphasizes that the case increase has been distributed widely across the state, rather than concentrated in just a few communities.
|Table 2: Highest Positivity Rates and Contribution to Positivity Rate Increase|
|Period Ending October 17, 2020|
|Highest Test Positivity Rate||Largest Contributers to Weekly Positivity Rate Increase|
|City/Town||14 Day Test Count||Test Positivity Rate (%)||City/Town||14 Day Test Count||Test Positivity Rate (%)||Relative Impact (%)|
The left three columns in Table 2 focus on the communities with the highest test positivity rate. There are some surprising names on the list, in particular Buckland and Chesterfield. This is because they have high positivity rates with very limited testing – Buckland had five positive cases in the two weeks ending October 17, and Chesterfield had three. These are hardly hotspots. However, four of the top ten communities for case incidence rates are also in the top ten for test positivity rates.
The right-hand columns focus on the communities making the largest contribution to the statewide positivity increase from 1.17% to 1.24%. Boston tops this list as well, even with a very small increase in test positivity from 0.74% to 0.8%, because of its large volume of testing. In the two weeks ending October 17, almost 20% of testing in Massachusetts was in Boston. In contrast, Gloucester and Saugus are not large testers, but each had test positivity rate increases of about 1%. The communities driving the increase in case incidence are also driving the increase in test positivity – the top ten communities in Table 1 and Table 2 are the same.