Vaccine data comes from the Illinois Comprehensive Automated Immunization Registry Exchange (I-CARE), a statewide database of immunization records. I-CARE includes doses administered in Illinois and some doses administered outside of Illinois and reported in I-CARE by Illinois providers. Doses administered by the federal Bureau of Prisons and Department of Defense are not currently reported in I-CARE. The Veterans Health Administration began reporting doses in I-CARE beginning September 2022.

The Chicago Department of Public Health (CDPH) uses the most complete data available to estimate COVID-19 vaccination coverage among Chicagoans, but there are several limitations that impact our estimates. Individuals may receive vaccinations that are not recorded in I-CARE, such as those administered in another state, causing underestimation of individuals with a completed primary series or updated booster. Inconsistencies in records of separate doses administered to the same person, such as slight variations in dates of birth, can result in duplicate first dose records for a person and overestimate of the number of people with at least one dose and underestimate the number of people with a completed primary series or booster dose.

More detailed descriptions of the data and downloadable files are available on the Chicago Data Portal.

Vaccination Status Definitions:

• At Least One Dose: People who’ve received at least one dose of a COVID-19 vaccine, including those with more than one dose.
• Completed Primary Series: People who’ve completed a primary series of COVID-19 vaccinations.
• Updated (Bivalent) Booster: People who’ve received at least one updated (bivalent) COVID-19 vaccine dose. Updated bivalent doses became available in Fall 2022 and were created with the original strain of COVID-19 and newer Omicron variant strains.

Coverage Estimates:

Vaccination coverage refers to the proportion of people in a given area who’ve been vaccinated. To calculate vaccination coverage, CDPH divides the number of people who’ve been vaccinated in a ZIP Code by the total estimated number of people who live in that ZIP Code. Coverage estimates by ZIP Code are capped at 99% since actual counts may exceed population estimates and lead to vaccination coverage greater than 100%. This is especially true of smaller ZIP Codes, such as those found in the Loop.

Due to ZIP Codes overlapping with areas outside the city boundaries, coverage estimates were not calculated for 60666, 60707, and 60827. Raw counts of individuals vaccinated can still be seen by hovering over these ZIP Codes on the map.

Population Estimates:

Population denominators are from the U.S. Census Bureau American Community Survey 1-year estimate for 2019 and can be seen in the Citywide, 2019 row of the Chicago Population Counts dataset.