Influenza activity is HIGH and increasing across Wisconsin.
Across the U.S. there were 21,652 (18.6%) influenza detections at clinical laboratories, from the 116,253 specimens collected last week. Of detected influenza viruses at public health laboratories, 97.8% were influenza A and 2.2% were influenza B. Among influenza A viruses, 55.5% were H3, 44.5% 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: 100%). The percentage of primary care patients with influenza-like illness (ILI) is at 6.1% and is well above baseline. ILI activity is very high in 18 states, high in 23 states, moderate in 4 states, low in 1 state, and minimal in 4 states; Wisconsin has high levels. 16 pediatric deaths (influenza A: 13); influenza B: 3) have been reported for the 2024-2025 season to date.
Wisconsin has recorded 671 hospitalizations for influenza this season. This is below the level in 2023-2024 (1,166) at this point.
The performance of rapid influenza testing is reasonable because of high levels of circulating virus.
The performance of rapid SARS-CoV-2 testing is moderate because of high levels of circulating virus.
There have been 67 confirmed and 7 probable cases (total = 73) detected in 12 states in 2024. Cases have been linked to dairy cattle (41), poultry (28), other animal (1), and unknown (4). There has been one death due to H5N1. The current public health risk is reported to be low.
https://www.cdc.gov/flu/hcp/antivirals/summary-clinicians.html
Antiviral treatment is recommended as soon as possible for any patient with suspected or confirmed influenza who:
Decisions about starting antivirals for patients with suspected influenza should not wait for laboratory confirmation. Empiric antiviral treatment should be started as soon as possible in the above priority groups. Clinicians can consider early empiric antiviral treatment of non-higher-risk outpatients with suspected influenza based upon clinical judgment if treatment can be initiated within 48 hours of illness onset.
As of January 10, 2025, Wisconsin has 2,527 confirmed cases statewide (age range: 1 month—90 years), with detections in 71 out of 72 counties. 49% of the cases have been in individuals aged 11–18 years. 100 infants have been identified with pertussis and 14 have been hospitalized. No deaths have been reported. The percent-positive rate for specimens submitted for pertussis tests is elevated at 1.6%.
Viruses associated with acute respiratory infections in Wisconsin primary care practices have been dominated by Influenza A, RSV, and SARS-CoV-2. SARS-CoV-2, influenza, and RSV detections are increasing. For the week ending 12/28/2024, 10.4% of 14,194 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 38.1 years old. 50% of patients have been female. 50% of patients identified a sick contact 1-3 days before illness onset and they typically present to the clinic 5.8 days after illness onset.
| Viruses in Circulation | Percent* in statewide laboratory surveillance | Percent** in primary care surveillance clinics |
|---|---|---|
| Influenza A | 37.8 | 25 |
| Influenza B | 0.8 | 0 |
| Seasonal Coronavirus*** | 1.5 | 0 |
| RSV | 24.3 | 25 |
| Parainfluenza | 0.8 | 0 |
| hMPV | 0.5 | 0 |
| Rhino/Enterovirus | 5.5 | 25 |
| Adenovirus | 0.5 | 0 |
| Bocavirus | 0.0 | 0 |
| SARS-CoV | 28.4 | 25 |
*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
SARS-CoV-2 activity is increasing across Wisconsin.
The 7-day average for patients hospitalized for COVID-19 in Wisconsin is 285 (increasing).
SARS-CoV-2 detections have stabilized over the past 1 week.
Across Wisconsin, 897,196 individuals (15.2% of the population) have received the updated 2024/2025 COVID-19 vaccine.
- 8.5% of all deaths during week 1 (December 29—January 4) were due to pneumonia, influenza, or COVID-19, and above the seasonal epidemic threshold.
- Variants: the national proportions of variants for the week ending December 7, 2024, were XEC (45%); KP.3.1.1 (24%); LP.8.1 (8%), MC.1 (5%); LF.7 (4%); and XEK (4%). 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.
