Covid-2019 epidemic trends: U.S. and Massachusetts

The following U.S. map, prepared by John Hopkins University researchers Holm and Forster, also distributed by Associated Press, shows prevalence of death from Covid-2019 by county, as reported to state and federal public health agencies through April 16, 2020.

U.S. county death rates from Covid-2019, through April 16, 2020

Covid-2019UsCountyPrevalence20200416

Source: Holm and Forster, John Hopkins University

The New York Times publishes its own estimates of cases and deaths attributed to Covid-2019 by states. The following table shows the ten most severely affected states, ranked by cases of illness per thousand state residents, as estimated for the about the same date as the foregoing U.S. map reflected.

Covid-2019 illnesses and deaths by states, April 17, 2020

State Illness count per 1,000 residents Death count per 1,000 residents
New York 229,642 11.8 12,822 0.66
New Jersey 78,467 8.8 4,840 0.43
Massachusetts 34,402 5.0 1,404 0.20
Louisiana 23,118 5.0 1,213 0.26
Michigan 29,952 3.0 2,226 0.22
Pennsylvania 30,121 2.4 1,027 0.08
Illinois 27,575 2.2 1,142 0.09
Florida 24,745 1.2 726 0.03
California 29,398 0.7 1,050 0.03
Texas 18,191 0.6 461 0.02

Source: New York Times, April 17, 2020

As the map shows and the table reflects, Massachusetts has developed one of the worst Covid-2019 epidemics of any state, just short of New Jersey and New York. Gov. Baker has taken criticism for issuing orders as public advisories rather than in forms enforceable by State Police. However, data for the spread of the state’s epidemic tend to show that Baker’s approach is working to some degree, although the state remains at high rates of cases and deaths, as reported daily.

Covid-2019 trends, Massachusetts, through April 16, 2020

MassachusettsCovid-2019EpidemicData20200417

Source: analysis of Massachusetts daily Covid-2019 data

The blue trend curve shows the slope of a semilograrithmic plot of cumulative cases versus epidemic days. The steep initial portion shows a rapidly growing epidemic, in which doubling time of the case load is shrinking. Day one is chosen to be the first day with a cumulative total of 20 or more reported deaths: March 26, 2020. Two days earlier, Gov. Baker issued his first restrictive order: that “non-essential” businesses close. On Day 7, Baker issued a second restrictive order, expanding the list of business that should close. On Day 14, Baker issued a “grocery guidance,” describing how retail stores that continue to operate should install and conduct protective measures. The blue trend above is using five days spanning each point to calculate the slope of the logarithm of case counts, so it stops two days short. The red trend above shows that the cumulative mortality has been climbing, as victims of the disease die: from about one percent initially to near four percent.

Each advisory order from Gov. Baker was followed in five to seven days by a sustained reduction in the epidemic’s spread, shown by a drop in the slope of a plot of the logarithm of cumulative case count. While Massachusetts has made progress, a goal of ending the state’s epidemic is far from attainment. Over the past week, ending April 17, the state has been reporting averages of about 1,900 new Covid-2019 cases and 115 deaths from Covid-2019 per day. Many governors of states with severe epidemics are taking cautious approaches to relaxing restrictions. California has been notably cautious. Gov. Newsom issued a declaration of emergency March 4, 2020, well before Gov. Baker’s declaration of emergency on March 10. Collaborating with governors of Washington and Oregon, Gov. Newsom said they would use “science to guide our decision-making and not political pressure”–rejecting hasty actions being promoted by the Trump administration.

– Craig Bolon, Brookline, MA, April 18, 2020


Geoff Mulvihill, Lacking U.S. coordination, states team up on when to reopen, Associated Press, April 18, 2020

Coronavirus in the U.S.: latest map and case count, New York Times, April 17, 2020 (as found April 18, 2020)

Zeke Miller, Alan Suderman and Kevin Freking, Trump proposes plan to reopen economy, Associated Press, April 16, 2020 (includes U.S. map of Covid-2019 prevalence by county from Holm and Forster at John Hopkins University)

COVID-19 cases, Massachusetts Department of Public Health, for April 16, 2020

Patricia Wen, Massachusetts confirmed coronavirus cases by city and town, Boston Globe, April 15, 2020

Mark Arsenault, Massachusetts experts push back on university’s bleaker Covid-2019 forecast, Boston Globe, April 15, 2020

Liz Kreutz and Alix Martichoux, Newsom unveils plan to ease California stay-at-home restrictions amid coronavirus pandemic, ABC News, April 14, 2020

Press releases related to COVID-19, Massachusetts Office of the Governor, March and April, 2020

Declaration of a state of emergency to respond to COVID-19, Massachusetts Office of the Governor, March 10, 2020

Governor Newsom declares state of emergency to help state prepare for broader spread of COVID-19, California Office of the Governor, March 4, 2020

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