Essex County Near State Average in COVID-19 Case Counts

(Updated to April 9, 2020)

Haverhill parents, teachers, school administrators and city leaders all need to make plans about education from home and reopening of schools closed due to coronavirus (COVID-19). Some have suggested that decisions to reopen businesses and schools might eventually be made county by county if patterns of coronavirus cases differ greatly among counties. This Benchmark Blog post looks at data available to date on coronavirus cases by county for the largest eastern Massachusetts counties.

This post considers cumulative and daily data on number of confirmed COVID-19 cases for the period for March 20 through April 9.  Case counts come from Massachusetts Department of Public Health (DPH). County population figures come from the UMass Donahue Institute. I computed cases per 1000 of county population (2018) for the largest Massachusetts counties and statewide. Keep in mind that counts reflect not only the incidence of the disease but also the amount of testing that is done. The state DPH reported 8,922 total patients tested on March 22 (the first day for which the number tested is reported for all laboratories) and 94,958 cumulative cases tested by April 9. About 19.9 percent of all cases tested were positive. The percentage positive has been rising steadily.

Chart 1 shows Essex County case counts per capita are rising at a similar rate to the statewide average, so close that until about April 3rd the lines closely overlap in the graph below. Essex and the other non-Boston areas appear to be on lower paths than Suffolk County. Essex County had been tracking near the state average, but its cumulative cases per capita is now 8 percent above the state average, and 18 percent above neighboring Middlesex County.

Chart 1

Chart 2 shows results for new cases reported daily. The greater day-to-day variation reflects the smaller numbers and possible day-of-the-week differences (fewer new cases reported on weekends) for testing and/or reporting. Suffolk County is tracking higher than other counties.

Chart 2

Chart 3 presents these data for new cases as a seven-day moving average. This smooths out the day-to-day variation and avoids any day-of-the-week reporting effects. Monitoring updates to this chart may help identify when the COVID spread begins to slow in Massachusetts counties. A slowing of the spread of the virus would be indicated by a downturn in the 7-day moving average curves.

Chart 3

The results indicate an upward trajectory for COVID-19 cases in all these counties. The results to date show that the less densely populated counties are tracking below Suffolk County in new cases per day per capita.  Over the past seven days (to April 9) Essex County had more new cases per capita than the state average or other eastern Massachusetts counties.

For Haverhill, these county-level results suggest that we in Essex County are on an upward path for coronavirus. Local closures and diligent social distancing can help keep Essex County’s trajectory flatter, and may, if effective, help produce fewer COVID-19 cases and deaths per capita than will occur in Boston.