We’ll update this story as new data and information become available, so check back frequently.
Students across Chicago and Illinois are back in classrooms. And this year, on top of the usual grades, attendance and test scores, parents have one more metric to track: How many coronavirus cases are showing up at my child’s school?
For starters, these are the official local trackers to watch:
Chicago Public Schools has created a COVID-19 dashboard for the 2021-22 school year.
Additionally, WBEZ is tracking vaccination rates for children ages 12 to 17 for the six-county Chicago metropolitan area by ZIP code.
But the blizzard of data points and technical terms may have left you wondering: Where does the data come from? How often is it updated? And, what’s missing? To consolidate your hunt for information, we’ve refashioned the CPS and IDPH source data into simple lookup tools — and explain the quirks of the underlying data in a section that we’ll update as we find out more.
Chicago Public Schools: Look up reported COVID-19 cases in your school
On Sept. 30, CPS changed the COVID-19 data they published from the number of confirmed cases and close contacts to the number of reported cases, confirmed or otherwise — both district-wide and by individual school. The school district started out the year publishing weekly reports but has started posting updates more frequently.
Utilizing CPS’ source data, WBEZ’s lookup tool lets you search for your school, compare schools side-by-side, and sort by number of reported cases.
Suburban Cook and the rest of Illinois: Look up COVID-19 outbreaks and 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.
Previously, two or more cases constituted an outbreak, but on Oct. 15, IDPH updated its definition of outbreaks following recommendations from the Centers for Disease Control and Prevention to adopt the Council of State and Territorial Epidemiologists’ guidance on school-associated outbreaks.
IDPH groups those outbreaks into ranges — less than five, five to 10, or more than 10 — in order to cloak the identities of children who have tested positive at any given school, especially very small ones. This data set trades precision for privacy, which makes it hard to detect large outbreaks or to analyze change over time.
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.
Illinois: Look up vaccination rates for teenagers 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.
If you’re really curious, here are 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, folks. 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.
We scrape IDPH’s website for the datasets on school outbreaks in schools, which update on Fridays.
We download CPS reports from their COVID-19 readiness website, which are updated “after impacted individuals are notified”. Previously, these reports were updated once a week on Wednesdays.
We calculate vaccination rates for children ages 12 to 17 by ZIP code using vaccination data from public records requests and publicly available population counts from the Census Bureau. Rates are the number of children between 12 and 17 years old who have received a complete vaccine series divided by the population of the same age group according to the Census Bureau’s five-year 2019 American Community Survey Estimates (Table B09001_009E). We confirmed this methodology with IDPH. These data update on a monthly basis.
We built the map of vaccination rates among 12 to 17-year-olds by joining the vaccination rate data by ZIP to a spatial file with every ZIP code tabulation area (ZCTA) in Illinois. ZCTAs are a Census Bureau spatial representation of the U.S. Postal Service ZIP codes, which are not geographic areas but rather a collection of mail delivery routes.