COVID-19: County Data

About our data

All data are laboratory-confirmed cases of COVID-19 that we extract from our live Wisconsin Electronic Disease Surveillance System (WEDSS) and freeze once a day. These numbers are the official state numbers, though counties may report their own totals independent of DHS. Combining the DHS and local totals may result in inaccurate totals.

Deaths must be reported by health care providers, medical examiners/coroners, and recorded by local health departments in order to be counted.

The number of people with negative test results includes only Wisconsin residents who had negative test results reported electronically to DHS or entered manually into the WEDSS electronic laboratory module. As a result, this number underestimates the total number of Wisconsin residents with negative test results.

Data shown below are subject to change. We strive for transparency and accuracy in our data, and as individual cases are investigated by public health, there may be corrections to the status and details of cases that result in changes to this information. Some examples of corrections or updates that may lead to changes to our data, such as case and negative counts and deaths going up or down, include: 

  • Update or correction of case's address, resulting in a change to their location of residence to another county or state,
  • Correction to laboratory result,
  • Correction to a case's status from confirmed to unconfirmed (for example, if they were marked as confirmed because a blood test detecting antibodies was positive instead of a test detecting the virus causing COVID-19),
  • De-duplication or merging and consolidation of case records,
  • Update of case's demographic information from missing or unknown to complete information.

For information on testing, see: COVID-19, testing criteria section.

Download data by county | Data dictionary (PDF)

Mapped county-level data

 

This chart is called an epidemic curve (or "epi curve"). It is used to track the number of illnesses over time and see when peaks of illnesses occur. This figure is showing data by when someone's symptoms began, also called symptom onset date (or by diagnosis date if symptom onset date is missing, or the patient did not have symptoms). Symptom onset date is more meaningful than using the date when the case was reported because it represents when illnesses occurred, instead of when the person was tested and the result was reported to public health.

When using symptom onset date, any downward trends that are seen during the most recent two weeks are usually not true decreases in illness and need to be interpreted with caution. This downward trend usually represents the data lag time; thus, data during the most recent two weeks are highlighted as preliminary data. When people have an acute illness, such as COVID-19, it may take several days for them to see a doctor or be tested. It also takes time for the tests to be completed and the results to be sent to public health to be included in case counts.

The figure titled "Cumulative total and newly reported COVID-19 cases by date confirmed" on our COVID-19: Wisconsin Cases webpage does present data by the date a case was reported as being laboratory-confirmed (and not by symptom onset date). These data are also available by county and can be downloaded by clicking the "Download data by county" hyperlink above.

 

 

This chart is called a cumulative epidemic curve. It shows the total (cumulative) number of confirmed cases, regardless of whether the cases have recovered. It represents how COVID-19 is spreading and expanding statewide and by county over time. An upward trend in the curve shows a time period where the number of cases are growing. A steeper curve in the chart signals that cases are growing at a higher rate.

 

This chart is called a mortality curve. It is used to track the number of deaths over time and see when peaks occur. This figure is showing data by when a person died. Date of death is more meaningful than using the date when the person's death was reported to public health.

When presenting data by the date of death, any downward trends that are seen during the most recent two weeks are usually not true decreases in deaths and need to be interpreted with caution. This downward trend usually represents the data lag time; thus, data during the most recent two weeks are highlighted as preliminary data. It takes time for patient deaths to be reported to public health and to be included in death counts.

The figure titled "Cumulative total and newly reported COVID-19 deaths by date reported" on our COVID-19: Wisconsin Deaths webpage does present data by the date a death was reported as being associated with COVID-19 (and not by date of death). These data are also available by county and can be downloaded by clicking the "Download data by county" hyperlink above.

 

 

This chart is called a cumulative mortality curve. It shows the total (cumulative) number of deaths among confirmed cases statewide and by county over time. An upward trend in the curve shows a time period where the number of COVID-19-related deaths are increasing. A steeper curve in the chart signals a higher rate of deaths.

Number of positive cases and deaths by county

 
Last Revised: June 23, 2020

 RESPONSE RESOURCES FOR WISCONSINITES — www.dhs.wisconsin.gov/covid-19/help.htm