Influenza is at low levels in Wisconsin.
Across the U.S. there were 4,151 (5.1%) influenza detections at clinical laboratories, from the 81,992 specimens collected last week. Of detected influenza viruses at public health laboratories, 97.1% were influenza A and 2.9% were influenza B. Among influenza A viruses, 60.8% were H3, 39.2% were H1, and 0.0% were H5. CDC has reported current match estimates between circulating and vaccine strains for this season (H3: 40%; H1: 100%; B: N/A). The percentage of primary care patients with influenza-like illness (ILI) is at 3.4% and is above baseline. ILI activity is high in 6 jurisdictions, moderate in 13 jurisdictions, low in 17 jurisdictions, and minimal in 19 jurisdictions; Wisconsin has low levels. Two pediatric deaths (influenza A: 2) have been reported for the 2024-2025 season to date.
Wisconsin has recorded 85 hospitalizations for influenza this season. This is below the level in 2023-2024 (274) at this point.
The performance of rapid influenza testing is reduced because of low levels of circulating virus.
The performance of rapid SARS-CoV-2 testing is reduced because of declining levels of circulating virus.
There have been 61 U.S. cases detected from 8 states in 2024. Cases have been linked to dairy cattle (37), poultry (21), other animal (1), and unknown (2). The first presumptive human case of H5N1 has been reported in poultry worked in Barron County, Wisconsin.
As of December 13, 2024, Wisconsin has 2,245 confirmed cases statewide (age range: 1 month—90 years), with detections in 69 out of 72 counties. 50% of the cases have been in individuals aged 11–18 years. 90 infants have been identified with pertussis and 12 have been hospitalized. No deaths have been reported. The percent positive rate for specimens submitted for pertussis tests is elevated at 2.1%.
Viruses associated with acute respiratory infections in Wisconsin primary care practices have been dominated by Rhinovirus. For the week ending 11/30/2024, 5.2% of 9,395 specimens tested across Wisconsin by the Wisconsin State Laboratory of Hygiene and clinical labs were positive for SARS-CoV-2. The most commonly identified gastopathogen is norovirus.
Over the past 4 weeks the typical ARI case has been 39.6 years old. 60% of patients have been female. 33% of patients identified a sick contact 1-3 days before illness onset and they typically present to the clinic 11.3 days after illness onset.
| Viruses in Circulation | Percent* in statewide laboratory surveillance | Percent** in primary care surveillance clinics |
|---|---|---|
| Influenza A | 11.2 | 14 |
| Influenza B | 0.8 | 0 |
| Seasonal Coronavirus*** | 2.7 | 7 |
| RSV | 11.7 | 7 |
| Parainfluenza | 6.5 | 14 |
| hMPV | 0.3 | 0 |
| Rhino/Enterovirus | 26.5 | 36 |
| Adenovirus | 2.0 | 7 |
| Bocavirus | 0.0 | 0 |
| SARS-CoV | 38.2 | 14 |
*estimate based on WSLH statewide data
** estimate based on primary care patients seen at five clinics in Dane County
*** includes HKU1, NL63, 229E and OC43
The 7-day average for patients hospitalized for COVID-19 in Wisconsin is 132 (stable).
SARS-CoV-2 detections have been increasing over the past 1 week.
Across Wisconsin, 857,981 individuals (14.5% of the population) have received the updated 2024/2025 COVID-19 vaccine.
6.3% of all deaths during week 49 (December 1—7) were due to pneumonia, influenza, or COVID-19, and below the seasonal epidemic threshold.
Variants: the national proportions of variants for the week ending December 7, 2024, were XEC (44%); KP.3.1.1 (39%); MC.1 (6%); LF.7 (3%); and LB.1.3.1 (2%). SARS-CoV-2 continues to be a rapidly diversifying virus.
Please refer to guidance provided by Wisconsin Department of Health Services and by the U.S. Centers for Disease Control and Prevention.
* The weekly influenza update is adapted from an email from Jon Temte, MD, PhD; Chair, Wisconsin Council on Immunization Practices; Professor, Department of Family Medicine and Community Health, University of Wisconsin School of Medicine and Public Health.
