US Influenza Activity is Declining But Still Remains Elevated

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Key updates from the CDC on influenza activity, hospitalizations, pediatric deaths, and current trends across the United States.

U.S. Influenza Activity Declines, Remains Elevated

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Image credits: CDC

According to the CDC's latest Influenza Surveillance Report, Seasonal influenza activity remains elevated but continues its downward trend for the second consecutive week. Despite the recent decrease, the 2024–2025 flu season has been classified as “high severity” for all age groups, marking the first such designation since the 2017–2018 season.

As of Week 13, the CDC estimates at least 45 million illnesses, 580,000 hospitalizations, and 25,000 deaths due to influenza. The cumulative hospitalization rate now stands at 121.9 per 100,000 population, which is the highest rate recorded since the 2010–2011 flu season.

Virus Activity and Circulating Strains

Public health laboratories reported 1,049 influenza virus detections this week:

  • Influenza A: 929 cases
  • Influenza B: 120 cases
  • No cases of A(H5) avian influenza or human-to-human transmission were identified.

Clinical and Epidemiologic Metrics

  • Outpatient Visits: 3.2% for influenza-like illness (ILI), remaining above the national baseline of 3% for 18 consecutive weeks
  • Test Positivity Rate: 9.7%, continuing a downward trend
  • Hospital Admissions: 9,364 new hospitalizations reported this week
  • Pediatric Deaths: 9 new deaths, bringing the seasonal total to 168
  • Influenza-Attributed Mortality: .9% of all US deaths

Pediatric deaths include 7 from influenza A and 2 from influenza B, bringing the 2024–2025 season close to the previous two years (187 in 2023–2024, and 207 in 2022–2023)

Antiviral Resistance

  • Oseltamivir resistance: Detected in one A(H1N1) and one A(H3N2) virus
  • Baloxavir reduced susceptibility: Observed in one A(H3N2) virus
  • Adamantanes: Not recommended due to ongoing resistance

Outpatient & Emergency Department Visits

  • ILI Outpatient Visits: 3.2%, stable nationally
  • Flu-Related ED Visits: 1.4% of all emergency visits, decreasing across all age groups

According to the CDC’s integrated respiratory surveillance:

  • Flu test positivity: down 9.7%
  • RSV positivity: down 4.1%
  • COVID-19 positivity: the same at 3.7%

COVID-19 mortality: .8%, slightly decreased
Influenza mortality: .9%, holding steady

The CDC continues to recommend annual influenza vaccination for everyone aged 6 months and older as long as influenza viruses are circulating. Early antiviral treatment is strongly encouraged for individuals at high risk of complications.

Reference
Centers for Disease Control and Prevention. Weekly U.S. influenza surveillance report: Key updates for week 13, ending March 29, 2025. FluView. April 4, 2025. Accessed April 7, 2025. https://www.cdc.gov/fluview/surveillance/2025-week-13.html
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