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These five charts show how COVID-19 is making a comeback in Mass.

Coronavirus testing in Dedham last month.Pat Greenhouse/Globe Staff/file

After a summer in which Massachusetts appeared to have quelled the coronavirus, the state is experiencing an alarming rise in cases.

Acknowledging the increases, Governor Charlie Baker recently issued new restrictions on restaurants and other businesses, urged people to get home every night by 10 p.m., and tightened his statewide mask order. He also said Friday the state would once again set up a field hospital at the DCU Center in Worcester.

The increases come amid record-breaking case numbers nationally and dire warnings that the United States is entering “COVID hell.” Experts have warned that cases would increase when colder weather forced more people inside, a scenario more conducive to the disease spreading. And they have warned that cases are inevitably followed by hospitalizations and deaths.


These five charts tell the story of the virus’s rebound in the state.

1. The number of cases reported per day

In this first chart, daily case totals are shown since the beginning of the pandemic, along with seven-day averages. The chart shows a mountain of cases per day in the spring as a terrified state hunkered down at home, a decrease in cases to a low point around late June, and then a disturbing rise in cases again starting in September.

2. Three different positivity rates that Massachusetts highlights in its daily dashboard

The lowest line on the chart is the positivity rate for testing at higher education institutions. In college testing programs, asymptomatic people can be tested repeatedly, which results in a low positivity rate. The line above it shows the rate of positive tests among all tests administered. And the top line shows the rate of positive tests when the higher education testing is removed.

3. A fourth kind of positivity rate

This is the positivity rate among people tested for the first time. The metric is not featured by the state on its daily dashboard, but it can be calculated from data files released by the state.


4. Traces of COVID-19 found in waste water at the Massachusetts Water Resources Authority’s plant on Deer Island

The waste water is being tested for copies of the virus as part of a pilot project. The hope is to pick up early signals of future rises in infections. Results are broken down by northern and southern sections of the MWRA system.

5. A look into a possible future

This chart shows the University of Massachusetts' weekly ensemble model of where the pandemic could go next for Massachusetts. Researchers at the lab combine numerous models to glean their collective wisdom and project the future several weeks ahead, in this case up to Dec. 5.

Cases per week, historic and projected.Reich Lab/UMass

Martin Finucane can be reached at Dasia Moore is the Globe Magazine's staff writer. E-mail her at Follow her on Twitter @daijmoore.