This is the best available count of COVID-19 cases in Michigan schools. Here’s what it means.

Michigan collects more information about COVID-19 than many other states, but it has not published a reliable count of coronavirus cases linked to schools.

The charts below contain the best available estimates of outbreaks and virus spread in schools across the state, which Chalkbeat compiled from state reports.

The numbers should be taken with a heaping grain of salt. For starters, state health authorities don’t track individual COVID-19 cases in schools. They track school-based outbreaks, defined as two or more potentially related cases on school grounds, meaning single might not be included in the data. What’s more, the numbers may have been collected using inconsistent methods. changed

We are publishing the data anyway to help readers better understand the available information about COVID-19 in schools. The state’s outbreak data is released weekly and broadcast by many local media outlets. changed

Though imprecise, the charts offer answers to basic questions that state officials have not answered: changed

How many cases of COVID-19 have been reported in schools? How has that changed over time? Where were the cases reported? Scroll down to see detailed answers to those questions.

Scroll down to see the graphics, and for more information about the data, including important caveats.

Tracking the data is especially important now, as Michigan students return to classrooms in greater numbers than at any time since September.

What to know about this school outbreak data

What is an outbreak?

A school outbreak is recorded when local health departments find “two or more COVID-19 cases that may have shared exposure on school grounds and are from different households.”

Cases linked to school sports or after-school activities are included.

How did Chalkbeat collect the data?

Since mid-September, Michigan health officials have posted weekly updates on coronavirus outbreaks in schools. Chalkbeat collected those updates from each week and produced a full count of coronavirus cases related to outbreaks in schools.

What’s missing from these numbers?

The data only includes cases that were part of an outbreak, defined as two or more cases on school grounds that may have shared an exposure. A single case on school grounds wouldn’t be included.

Districts are required to publish tallies of all COVID-19 cases — not just those that meet the epidemiological standard for an outbreak. But no one has collected those counts from the websites of more than 800 districts in the state.

What’s more, there is little assurance that schools are using consistent methods to report the data to health authorities.

How recent is this data?

State data is updated weekly on Mondays. This page includes data as of Monday, February 22nd.

How many cases of COVID-19 have been reported in schools?

More than 3,700 cases have been reported in schools as part of outbreaks. The number of school-related cases rose amid the November wave of COVID-19, then fell steadily after Thanksgiving.

How many schools reported outbreaks?

Of 711 school districts that planned to offer some form of in-person instruction since September, 253 had at least one outbreak. Outbreaks represent as few as two COVID-19 cases. Schools often remained open during outbreaks, with only a handful of individuals required to isolate.

Where were outbreaks reported?

Outbreaks were reported in schools across the state, in urban, rural, and suburban areas. Charter schools, private schools, and traditional K-12 schools reported outbreaks. Outbreaks were reported in schools with all grade levels.

What do these numbers say about about the safety of reopening classrooms?

With a new, more contagious variant of COVID-19 appearing in Michigan, data from the fall have a limited ability to predict how safe classrooms will be now.

In any case, researchers who looked at the safety of Michigan classrooms during the fall didn’t even use these numbers.

Instead, they tracked how COVID-19 moved through communities, then linked those numbers with school reopenings. Two papers that used a version of this method — including one focused on Michigan — found that reopening schools didn’t accelerate the spread of COVID-19 in communities, as long as cases were low or moderate (below 21 daily cases per 100,000 people, according to one estimate).

The conclusion: Schools were able to limit the spread of COVID-19 inside their buildings as long as the virus wasn’t raging out of control in their communities.

Researchers don’t know whether that will hold true this spring.

Do schools close when there is an outbreak?

Sometimes. In lucky cases, health officials determine that the infected people only had contact with a few others, and the school can continue operating while only a handful of people isolate at home. Masking, social distancing, good ventilation, and small class sizes can reduce the spread of COVID-19 in schools.

This article was originally posted on This is the best available count of COVID-19 cases in Michigan schools. Here’s what it means.