WBEZ has researched the official data sets that show the impact of coronavirus on schools in Illinois – including case counts, close contacts and vaccination rates.

We’ve consolidated some of the most important information on this page, reporting the latest numbers from the Illinois Department of Public Health and Chicago Public Schools as soon as they are available. This page updates automatically so check back regularly.

CPS cases, vaccination rates by school

Utilizing CPS’ source data, WBEZ’s lookup tool lets you search for your school and see its total student and adult positive count over time dating back to Aug. 29.

You can also search for your school’s reported student vaccination rate as of Jan. 18, 2022.

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The rest of Illinois: outbreaks, potential exposures by school

The Illinois Department of Public Health handles data collection for areas outside of Chicago, including suburban Cook and beyond. Instead of providing precise numbers as CPS does, the state health department reports on outbreaks: clusters of three or more cases linked by time and location.

Here, we’ve collected and republished IDPH data about COVID-19 outbreaks in a lookup table. The state health department’s online tracker doesn’t specify where schools are located, but we’ve scraped the underlying data that powers the IDPH tracker and found that it includes more information than the website displays. So you can use the tool below to search by school, city or county.

IDPH also reports potential exposures, which include confirmed and probable cases based on contact tracing. However, this data set does not include city name, so you can only search by school or county.

Youth vaccination rates by ZIP code

WBEZ is tracking vaccination rates for children ages 12 to 17 by ZIP code. We intend to update these figures on a monthly basis.

You can use the lookup tool below to either search vaccination rates by ZIP code or zoom in on the map.

The technical details

These data sets have various omissions that make it difficult to draw big-picture conclusions about the spread of coronavirus in schools. Here are some of the issues we’ve identified.

Apples and oranges. IDPH and CPS publish similar but not identical data, which makes it difficult to compare cases between, say, a CPS school and a school in suburban Cook County. CPS reports exact case totals, while IDPH only describes outbreaks in broad numerical ranges.

Some reporting is duplicative. We noticed that a smattering of Chicago schools appear in IDPH data. This can happen when a CPS school reports an outbreak to the Chicago Department of Public Health, which in turn passes the information to the state health department. When this happens, the school shows up in both CPS and IDPH databases.

This can lead to inconsistencies. Local and state tallies can get out of sync as different agencies investigate COVID-19 cases, creating multiple streams of data. Take Barry Elementary School in Hermosa, for example. According to IDPH potential exposures data, there were between two to four COVID-19 cases where individuals reported Barry as a place they had visited as of Sept. 10. But if you look up Barry Elementary in the CPS database, the tool reports 0 confirmed cases as of Sept. 15.

We’re not sure why the CPS and the health department information don’t match. To better understand how this process works, we’ve filed a Freedom of Information Act request with the Chicago Department of Public Health.

The data are delayed — and the lag time is hard to predict. If you are a CPS teacher or parent, you may have been recently notified of a COVID-19 case in your school that was not reflected in the district’s tracker. Similar anecdotes of delayed contact tracing reports are piling up.

CPS updates are sporadic. CPS started out the school year posting weekly reports on Wednesdays, but began posting more frequent updates in late September. Its tracker previously did not indicate when records were last posted, making it unclear if case counts were up to date. On Sept. 30, CPS announced that it would begin updating its data daily.

Agencies can change numbers after publication. CPS recently posted the following message on its tracker: “On September 20, CPS discovered a data issue in its reporting platform producing duplicate cases within the Actionable Cases graph below. Cases that were either reported more than once or were later withdrawn due to this issue have now been removed from the total case count.”

IDPH cautions users that all data is “provisional,” which means its numbers are subject to updates, including retroactive ones. This presents a challenge when looking at how COVID-19 cases, outbreaks and potential exposures change over time because IDPH only posts current outbreak data and removes historical data from its website.

Agencies can change the kinds of data they publish. Over the 2021-2022 winter break, CPS started sharing only the number of COVID-19 cases at individual schools that were confirmed by contact tracers. This change was heavily criticized for giving parents a less accurate and timely picture of what is happening in their children’s schools. On Feb. 24, CPS notified parents via email that it would break out self-reported cases separately from those identified by in-school screening. On the same day, CPS made several changes to its application programming interface.

Charmaine Runes is WBEZ’s data/visuals reporter. Follow her @maerunes. Matt Kiefer is WBEZ’s data editor. Follow him @matt_kiefer