On February 14, 2025, the US Centers for Disease Control and Prevention (CDC) issued a Weekly US Influenza Surveillance Report regarding the increase in influenza cases in the current season. Based on data available for the week ending February 8, 2025, this season is classified as a high severity season for all age groups (children, adults, older adults) for the first time since 2017-2018. Outpatient respiratory illness is higher than it has been all season and is above the baseline nationally for the eleventh consecutive week.

According to the CDC, at least 29 million illnesses, 370,000 hospitalizations, and 16,000 deaths from flu have occurred so far this season. The highest peak weekly hospitalization rate observed across all seasons since 2010-2011 is during Week 5 (12.8 per 100,000 population). The highest cumulative hospitalization rate across all seasons since 2010-2011 is observed in Week 6 (78.1 per 100,000 population).

When examining rates by age, the highest cumulative hospitalization rate per 100,000 population was among adults aged 65 years and older (241.1), followed by adults aged 50-64 years (92.0), children aged 0-4 years (66.4), adults aged 18-49 (33.2), and children aged 5-17 (23.4). Among hospitalized adults, the most commonly reported medical conditions were hypertension, cardiovascular disease, metabolic disease, and obesity. Among hospitalized children, 53 % had at least one reported underlying medical condition. The most commonly reported were asthma, followed by neurologic disease and obesity.

Mortality

The first time that the percentage of deaths for influenza (1.7%) was higher than the percentage of deaths for COVID-19 was the week ending January 25, 2024. However, the percentage of deaths for influenza has continued to increase and is 2.6% for the week ending February 8, 2025. A total of 68 pediatric deaths were associated with seasonal influenza.

Laboratory data

The percent of specimens testing positive for influenza at clinical labs is higher than any peak week going back to the 2015-2016 and 2010-2011 seasons, respectively. 23,917 laboratory-confirmed influenza-associated hospitalizations were reported between October 1, 2024, and February 8, 2025. Among all hospitalizations, 23,399 (97.8%) were associated with influenza A virus, 387 (1.6%) with influenza B virus, 20 (0.1%) with influenza A virus and influenza B virus co-infection, and 111 (0.5%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 2,921 (53.5%) were A(H1N1) and 2,539 (46.5%) were A(H3N2).

During Week 6, of the 4,214 viruses reported by public health laboratories, 4,079 were influenza A and 135 were influenza B. Of the 3,146 influenza A viruses subtyped during Week 6, 1,742 (55.4%) were influenza A(H1N1)pdm09, 1,404 (44.6%) were A(H3N2), and zero were A(H5). 

Source:

Weekly US Influenza Surveillance Report: Key Updates for Week 6, ending February 8, 2025.  

https://www.cdc.gov/fluview/surveillance/2025-week-06.html