The Cook County Department of Public Health threw us a curveball last week when they unveiled newly reconfigured municipal COVID-19 data. The shift in data reflected a couple of things going on behind the scenes at the county level.

First, in an attempt to get the clearest picture of where the county needs to focus its efforts in educating and encouraging people to get vaccinated, the county used the new 2020 Census data to give the most up-to-date snapshot for vaccination rates.

With the county aiming for 70 percent of every town’s population to receive at least one dose of the COVID-19 vaccine, that census data is key. In villages like Riverside, North Riverside and Brookfield, where populations all grew, real-time vaccination rates dropped.

As recently as last week and for months before that, the county was reporting that more than 90 percent of Riverside’s residents had been vaccinated, while North Riverside had barely eclipsed 40 percent.

If those numbers seemed skewed — they certainly raised red flags for us, because the two towns share the same ZIP code — it’s because they were.

In addition to using the most up-to-date census figures, the Cook County Department of Health revealed last week that its new data reflected its effort to geomap the addresses of every person who contracted COVID-19 and who had been vaccinated.

It was the geomapping piece that dramatically affected the numbers the county and, by extension, the Riverside-Brookfield Landmark had been reporting on case totals and vaccination rates.

Essentially, the new data wiped away roughly 20 months of data for Riverside and North Riverside that the Landmark has been tracking since March 2020. The Landmark reached out to the county in the wake of last week’s announcement in order to get a new data set for each village that tracks COVID-19 cases on a weekly basis since the beginning of the pandemic.

The Landmark received that data late on the morning of Nov. 9 and is working through it, but an early assessment is that it’s not perfect, since for the weeks that there were four or fewer new cases in each town, an exact number was not provided.

So we have a bit of work to do on our end to recreate the COVID-19 case graph that we’ve been using to give local residents a picture of how the pandemic has been impacting the villages.

The new data has not had an effect on our weekly case counts in Brookfield, but it sure has in North Riverside and Riverside, although the total combined number of cases for those two villages still tracks.

The new data allocation also had no effect on tracking fatal cases of COVID-19 in Brookfield, Riverside and North Riverside. The Cook County Medical Examiner tracks those cases separately and the Landmark routinely checks this data for its accuracy and has noted over time when the medical examiner’s address information does not reflect the proper municipality.

That’s why we know there have been at least four COVID-19 deaths in North Riverside while the medical examiner’s data only shows three. The agency misattributed one North Riverside address to Riverside. We also found one instance where a Riverside resident’s address was attributed to the hospital in which that person died.

It’s frustrating, but the good news is this new municipal-level data appears to be much more reliable, and it’s what we’ll be tracking going forward.