Seasonal influenza kills between 6,300 and 52,000 people per year in the United States, based on CDC estimates covering 2010 through 2025. The wide range reflects how much flu severity shifts from one season to the next, depending on which virus strains circulate and how well the population’s immunity matches up. In the most recent fully reported season (2023–2024), an estimated 28,000 people died from flu-related causes.
Why the Range Is So Wide
Flu seasons are not created equal. A mild season might kill closer to 6,000 people, while a severe one can push past 50,000. The difference comes down to which influenza strains dominate in a given year, how effective that season’s vaccine turns out to be, and how much prior immunity the population carries from earlier exposures. When a strain drifts significantly from what people’s immune systems recognize, hospitalizations and deaths spike.
The 2023–2024 season landed in the middle of the historical range: roughly 40 million people got sick, 470,000 were hospitalized, and 28,000 died. That’s a typical moderate season, not a mild one and not a worst case.
The Real Numbers Are Higher Than Death Certificates Show
If you looked only at death certificates listing influenza as the cause, you’d get a much smaller number than the CDC’s estimates. That’s because flu is significantly underreported on death records, for several reasons. Many people who die from flu complications are never tested for the virus, especially older adults who are most vulnerable. Even when testing does happen, the virus is only detectable for a limited window, and many people don’t seek care during that window. Perhaps most importantly, flu often kills indirectly by triggering pneumonia, heart failure, or other complications that end up listed as the official cause of death instead.
To get a more accurate picture, the CDC uses statistical modeling. The agency tracks laboratory-confirmed flu hospitalizations through a surveillance network, adjusts for undertesting, then applies a ratio of deaths to hospitalizations. It also examines death certificates coded for pneumonia, respiratory illness, and circulatory disease to capture deaths that occurred outside hospitals. The result is an estimate, not an exact count, but it’s far closer to reality than raw death certificate numbers.
Who Is Most at Risk
Flu deaths are heavily concentrated among older adults. People 65 and older account for about 71% of all flu-related deaths in a typical season, despite making up a much smaller share of the population. Adults aged 50 to 64 account for another 21%. Together, those two groups represent more than 9 out of 10 flu deaths.
Children are at the other end of the vulnerability spectrum. Pediatric flu deaths have been nationally reportable since 2004, giving a clearer (though still incomplete) picture. In the 2023–2024 season, 210 laboratory-confirmed deaths were reported in children under 18. The 2024–2025 season saw a jump to 293 pediatric deaths. These are confirmed cases only, so the true number is likely higher. Still, children account for a very small fraction of total flu mortality. The overwhelming burden falls on people with aging immune systems or chronic health conditions.
How Flu Actually Kills
Most flu deaths aren’t caused by the virus destroying the lungs on its own. The more common path involves secondary infections. After the initial viral illness, the immune system goes through a kind of reprogramming that can leave a person temporarily immunosuppressed for weeks. Researchers have described this as an “immunological scar,” where the processes that normally dial down inflammation after an infection overshoot, leaving the body less able to fight off new threats.
That creates an opening for bacteria that normally live harmlessly in the body. Everyday bacteria that a healthy immune system handles easily can suddenly cause life-threatening pneumonia in someone recovering from a severe flu infection. Pneumonia and other lower respiratory infections are the most common direct cause of flu-related death.
In some cases, the immune response itself becomes the problem. The body floods the bloodstream with inflammatory signals, a process that can spiral into sepsis. In sepsis, it’s not just the pathogen doing damage. The immune system’s own cells go into overdrive, attacking healthy tissue along with the infection. This is more likely in people whose bodies are already weakened by the initial viral illness or by underlying chronic conditions.
Flu vs. COVID-19 Mortality
During the pandemic, flu and COVID-19 were frequently compared. The data from England and Wales (where tracking was particularly detailed) showed that COVID-19 was the underlying cause of death in more than four times as many cases as flu and pneumonia combined between March 2020 and April 2022. At peak waves, COVID deaths among people aged 40 to 79 were nearly 32 times higher than flu and pneumonia deaths in the same age groups.
The age distribution of deaths also differs. About 74% of flu and pneumonia deaths in that period occurred in people 80 and older, compared with 58% of COVID deaths. COVID killed a larger share of people in middle age: roughly one in three COVID deaths were in people aged 60 to 79, versus one in five for flu and pneumonia. Both diseases disproportionately affect older adults, but COVID reached further down the age spectrum during its most severe waves. In the U.S., COVID mortality has dropped substantially since the early pandemic years, but it still typically exceeds flu deaths in a given year.
What a “Typical” Season Looks Like
A useful way to think about the flu’s annual toll: in most years, somewhere between 12,000 and 52,000 Americans die, with the majority of seasons clustering in the range of 20,000 to 40,000 deaths. The lowest estimates (around 6,300) correspond to unusually mild seasons. The 2023–2024 figure of 28,000 deaths is a reasonable benchmark for what a moderate season produces, alongside roughly 470,000 hospitalizations and 40 million symptomatic infections. That means the vast majority of people who catch the flu recover without serious complications, but the sheer number of infections means the small percentage who don’t still translates to tens of thousands of deaths each year.