COVID-19: Wisconsin Cases and Deaths

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 shows data by when someone’s symptoms began, also called symptom onset date. For some data, symptom onset date is missing or the patient did not have symptoms. In that case, the diagnosis date is used. Symptom onset date is more meaningful than using the date when the case was reported because it allows us to more closely track when illnesses occurred.

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; so, data during the most recent two weeks are highlighted as preliminary data. When people have a serious 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.

Please note:

• January 15-17, 2022: The WEDSS system was updated to allow for auto-importing of positive tests. Daily case numbers for this period were elevated due to processing the backlog of records.
• May 27, 2021: This visualization is using an updated data file that allows corrections due to quality assurance to be counted on the day when a case or death was first reported, rather than affecting the current daily cases or deaths. The new historical data file behind this improved method is available for download in the "Download our data" section.
• October 16-18, 2020: The WEDSS system underwent routine maintenance and enhancements. Due to this temporary pause in reporting, multiple days of data were uploaded at once, affecting the single day count for the visualizations during that time.

Data source: Wisconsin Electronic Disease Surveillance System (WEDSS).

Read our Frequently Asked Questions for more information on how cases of COVID-19 are reported to WEDSS.

Every morning by 9 a.m., we extract the data from WEDSS that will be reported on the DHS website at 2 p.m. These numbers are the official DHS numbers. Counties may report their own case and death counts on their own websites. Because WEDSS is a live system that constantly accepts data, case and death counts on county websites will differ from the DHS counts if the county extracted data from WEDSS at a different time of day. Please consult the county websites to determine what time of day they pull data from WEDSS. Combining the DHS and local totals will result in inaccurate totals.

Confirmed cases of COVID-19: Unless otherwise specified, the data described here are confirmed cases of COVID-19 reported to WEDSS. Cases are classified using the national case definition established by the CDC. Confirmed cases are those that have positive results from diagnostic, confirmatory polymerase chain reaction (PCR) tests or nucleic acid amplification tests (NAT) that detect genetic material of SARS-CoV-2, the virus that causes COVID-19. Illnesses with only positive antigen or positive antibody test results do not meet the definition of confirmed and are not included in the number of confirmed cases.

COVID-19 Deaths: Unless otherwise specified, COVID-19 deaths reported on the DHS website are deaths among confirmed cases of COVID-19 that meet the vital records criteria set forth by the CDC and Council of State and Territorial Epidemiologists (CSTE) case definition. Those are deaths that have a death certificate that lists COVID-19 disease or SARS-CoV-2 as an underlying cause of death or a significant condition contributing to death. Deaths associated with COVID-19 must be reported by health care providers or medical examiners/coroners, and recorded in WEDSS by local health departments in order to be counted as a COVID-19 death. Deaths among people with COVID-19 that were the result of non-COVID reasons (e.g., accident, overdose, etc.) are not included as a COVID-19 death. For more information see the FAQ page.

Probable cases of COVID-19 and deaths among probable cases. Some visualizations include the option of including information on probable cases of COVID-19 and deaths among probable cases of COVID-19. Cases are classified using the national case definition established by the CDC and the CSTE. A person is counted as a probable* case of COVID-19 if they are not positive by a confirmatory laboratory test method (for example, a PCR, or NAT test), but have met one of the following:

1. Test positive using an antigen test method.
2. Have symptoms of COVID-19 AND known exposure to COVID-19 (for example, being a close contact of someone who was diagnosed with COVID-19) and no molecular or antigen test was performed.
3. COVID-19 or SARS-CoV-2 is listed on the death certificate.

*Prior to August 19, 2020, probable cases also included those that had a positive antibody test which detects COVID-19 antibodies in the blood. For more details on this transition, see the CDC’s statement.

Deaths among probable cases are those that meet one of the following criteria:

• A probable case of COVID-19 is reported to have died from causes related to COVID-19.
• A death certificate that lists COVID-19 disease or SARS-CoV-2 as an underlying cause of death or a significant condition contributing to death is reported to DHS but WEDSS has no record of confirmatory laboratory evidence for SARS-CoV-2.

Data shown are subject to change. For more information see the FAQ page. 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 result in the case or death counts 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.

We plan to update our data Tuesday through Friday by 2 p.m.

This chart is called a mortality curve. It is used to track the number of deaths over time and see when peaks occur. This chart 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.

Please note:

• October 16-18, 2020: The WEDSS system underwent routine maintenance and enhancements. Due to this temporary pause in reporting, multiple days of data were uploaded at once, affecting the single day count for the visualizations during that time.

Data source: Wisconsin Electronic Disease Surveillance System (WEDSS).

Read our Frequently Asked Questions for more information on how cases of COVID-19 are reported to WEDSS.

Every morning by 9 a.m., we extract the data from WEDSS that will be reported on the DHS website at 2 p.m. These numbers are the official DHS numbers. Counties may report their own case and death counts on their own websites. Because WEDSS is a live system that constantly accepts data, case and death counts on county websites will differ from the DHS counts if the county extracted data from WEDSS at a different time of day. Please consult the county websites to determine what time of day they pull data from WEDSS. Combining the DHS and local totals will result in inaccurate totals.

Confirmed cases of COVID-19: Unless otherwise specified, the data described here are confirmed cases of COVID-19 reported to WEDSS. Cases are classified using the national case definition established by the CDC. Confirmed cases are those that have positive results from diagnostic, confirmatory polymerase chain reaction (PCR) tests or nucleic acid amplification tests (NAT) that detect genetic material of SARS-CoV-2, the virus that causes COVID-19. Illnesses with only positive antigen or positive antibody test results do not meet the definition of confirmed and are not included in the number of confirmed cases.

COVID-19 Deaths: Unless otherwise specified, COVID-19 deaths reported on the DHS website are deaths among confirmed cases of COVID-19 that meet the vital records criteria set forth by the CDC and Council of State and Territorial Epidemiologists (CSTE) case definition. Those are deaths that have a death certificate that lists COVID-19 disease or SARS-CoV-2 as an underlying cause of death or a significant condition contributing to death. Deaths associated with COVID-19 must be reported by health care providers or medical examiners/coroners, and recorded in WEDSS by local health departments in order to be counted as a COVID-19 death. Deaths among people with COVID-19 that were the result of non-COVID reasons (e.g., accident, overdose, etc.) are not included as a COVID-19 death. For more information see the FAQ page.

Probable cases of COVID-19 and deaths among probable cases. Some visualizations include the option of including information on probable cases of COVID-19 and deaths among probable cases of COVID-19. Cases are classified using the national case definition established by the CDC and the CSTE. A person is counted as a probable* case of COVID-19 if they are not positive by a confirmatory laboratory test method (for example, a PCR, or NAT test), but have met one of the following:

1. Test positive using an antigen test method.
2. Have symptoms of COVID-19 AND known exposure to COVID-19 (for example, being a close contact of someone who was diagnosed with COVID-19) and no molecular or antigen test was performed.
3. COVID-19 or SARS-CoV-2 is listed on the death certificate.

*Prior to August 19, 2020, probable cases also included those that had a positive antibody test which detects COVID-19 antibodies in the blood. For more details on this transition, see the CDC’s statement.

Deaths among probable cases are those that meet one of the following criteria:

• A probable case of COVID-19 is reported to have died from causes related to COVID-19.
• A death certificate that lists COVID-19 disease or SARS-CoV-2 as an underlying cause of death or a significant condition contributing to death is reported to DHS but WEDSS has no record of confirmatory laboratory evidence for SARS-CoV-2.

Data shown are subject to change. For more information see the FAQ page. 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 result in the case or death counts 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.

We plan to update our data Tuesday through Friday by 2 p.m.