Hospitalizations due to the flu reached their highest levels in over a decade last season, according to CDC data, which suggests that another intense flu season may be on the horizon.
During the 2024-2025 flu season, there was a noticeable spike in severe cases, with nearly 39,000 individuals hospitalized between October and April. This marked a significant increase, resulting in a hospitalization rate of 127.1 per 100,000 people—more than double the average seen over the previous 14 flu seasons and the highest since at least 2010.
The peak of the season occurred in early February, when admission rates surged to the highest levels recorded in a decade.
Interestingly, the majority of those hospitalized—over 70 percent—had not received the flu vaccine. Those who were hospitalized experienced outcomes consistent with previous severe flu seasons.
About 17 percent of hospitalized patients required ICU care, while six percent needed ventilators for breathing, and three percent succumbed during their hospital stay. However, the CDC did not provide specific death figures. The most common complications included pneumonia, sepsis, and kidney failure.
Despite the challenges, around 85 percent of hospitalized patients were administered antiviral medications like Tamiflu, which can lessen both the severity and duration of the flu. However, the treatment was less common among children and adolescents, likely due to a belief that their strong immune systems can handle mild illnesses.
This assumption can be misleading. The CDC did not offer a specific count of pediatric deaths, but an estimate from the American Academy of Pediatrics indicated that the death toll among children last season reached 216, making it the deadliest flu season for U.S. children in non-pandemic years.
Every year, scientists from the WHO and the CDC convene to determine which flu strains will be prioritized for the next vaccine. Though the vaccine may not perfectly match circulating viruses, it generally reduces the likelihood of requiring medical attention by 30 to 60 percent and can significantly minimize symptom severity.
Since immunity wanes as the season progresses, the CDC recommends getting vaccinated in October. Annual flu shots are advised for everyone six months and older, even for healthy individuals with no underlying conditions.
Health officials face the challenge of predicting which viruses will dominate in the upcoming season. The effectiveness of the flu vaccine largely depends on the accuracy of these predictions. Last season, the CDC estimated vaccine effectiveness at preventing hospitalizations ranged from 41 to 78 percent.
For less severe infections that still required medical attention, effectiveness varied from 32 to 60 percent.
Most individuals with the flu recover within days or a week, but the virus remains a serious threat, causing about 36,000 deaths annually in the U.S. It can be particularly dangerous for older adults, those with respiratory issues like asthma, individuals with obesity or heart disease, and the unvaccinated.
The flu can lead to life-threatening complications beyond the familiar symptoms like fever and fatigue, including pneumonia, bloodstream infections such as sepsis, and inflammation of vital organs.
The latest CDC data is drawn from their FluSurv-NET surveillance system, which monitors around 300 hospitals across 14 states and represents about 31 million people, or roughly nine percent of the U.S. population.
This system tracks severe, laboratory-confirmed flu cases that necessitate hospitalization, gathering detailed clinical information from a subset of patients. In young children, asthma was identified as the most significant risk factor for hospitalization, affecting 14 percent of toddlers and nearly 40 percent of school-aged children.
For young adults aged 18 to 49, obesity emerged as a major risk factor, present in about 44 percent of hospitalized patients. In adults aged 50 to 64, chronic metabolic diseases, particularly diabetes, were the most common, affecting 45.6 percent of patients. Among seniors, cardiovascular disease was the leading risk factor, affecting 57 percent of those aged 65 to 74 and 69 percent of those aged 75 and older.
This flu season was notably severe, with hospitalization rates across all age groups two to three times higher than the average of the past 14 seasons. Adults 75 and older faced the highest rates at nearly 599 hospitalizations per 100,000 people, representing the second highest for seniors but the worst recorded for other age demographics.
A significant 30 percent of patients developed pneumonia, the most common complication, while 18.5 percent faced sepsis, and another 18 percent experienced acute kidney failure.
The primary cause of this severe season was influenza A viruses. Although the H1N1 strain was more widespread, it resulted in higher hospitalization rates among older adults compared to the H3N2 strain, marking a reversal from the previous severe season in 2017-2018.
The 2025-2026 flu vaccine will target three strains: an A(H1N1)-like virus, an A(H3N2)-like virus, and a B/Victoria lineage-like virus. Flu shots are typically covered by insurance, as nearly all insurers are required to cover CDC-recommended vaccinations, though the cost can range from $20 to $120 without insurance. Public clinics often provide them for free.
