The CDC estimates flu has killed between 16,000 to 79,000 people (including 68 children), infected between 29 million and 51 million people, and hospitalized up to 820,000 since Oct. 1. This season is now being regarded as the most severe flu season in the U.S. in 15 years.
Here’s everything you need to know about this extreme flu season:
The toll of the 2024-25 flu season
Flu activity has risen significantly in recent weeks, placing significant pressure on the U.S. healthcare system.
Seven facts to know:
- The CDC has classified this season as high severity for all age groups for the first time since the 2017-18 season.
- Earlier this month, outpatient visits for flu-like illness reached the highest weekly rate seen since the 2009-10 swine flu pandemic.
- Emergency department visits linked to the virus shot up nearly 30% last week compared to the week prior. Nationally, ED visits are very high for flu and moderate for RSV, while visits for COVID-19 are low.
- For the first time since the beginning of the pandemic, more people in the U.S. died of flu than from COVID-19 for the week ending Jan. 25. Over the past two weeks, the CDC reports that flu deaths have outpaced COVID-19 deaths and now make up 2.6% of all deaths for the most recent week, compared to 1.5% for COVID-19.
- Flu hospitalizations have also surpassed those for COVID-19 for the first time since the pandemic. As of Feb. 8, the cumulative flu hospitalization rate was 78.1 per 100,000, marking the highest figure seen for this time period since the 2010-11 season.
- In the week ending Feb. 8, more than 24,000 flu patients were hospitalized. Nationwide, flu patients accounted for 5% of occupied hospital beds nationwide, HHS data shows.
- Overall, flu activity was high or very high in every state but Alaska, Hawaii, North Dakota and Montana in the week ending Feb. 8.
What is contributing to the 15-year high in flu activity?
- H1N1- and H3N2-related variants, both type A flu strains, are the predominant flu viruses circulating this season. Flu A is generally more severe and is the only variant known to cause pandemics — including the 1918 flu pandemic. The current vaccine was engineered to protect against both of these variants.
- Low vaccination rates may also be at play. This year only about 45% of U.S. adults and children were vaccinated against the flu, CDC data shows. That’s lower than normal for children and is well below the CDC’s goal of 70% coverage, according to TIME. Experts suggest misinformation about vaccines and post-COVID-19 vaccine fatigue may be contributing factors to the lower inoculation rate.
- This season’s vaccine may be offering only modest protection. In five South American countries — where the H3N2 strain was also dominant — vaccines reduced the risk of hospitalizations by about 35% among high-risk groups including young children, older adults, and people with underlying health conditions, according to a CDC analysis. The agency said vaccine effectiveness may be similar in the Northern Hemisphere. Comparatively, the vaccine last season had a 51.9% effectiveness in those South American countries.
- This season, there appears to be two major peaks of illness: One from late December to early January, and another spike in recent weeks.
- COVID-19 precautions reduced flu cases during the pandemic but may be contributing to weakened population immunity, leading to the high severity this season, Mark Mulligan, MD, chief of infectious disease and director of the vaccine center at NYU Langone Health in New York City, told The Washington Post.
What else is different about flu season this year?
Norovirus has made waves this virus season alongside the flu, RSV and COVID-19, creating a quadruple threat for the U.S. In January, norovirus surged to levels not seen in more than a decade, with rates still high in some areas. RSV hospitalization rates also remain elevated in many areas of the country. Together, these viruses have placed additional burdens on hospitals already facing high volumes of flu patients.