How Many People Die From the Flu Each Year?

Flu season in the United States, which runs from October through May, normally claims tens of thousands of lives every year. But there's never an exact number of flu deaths for any year—that's because the flu is not a reportable disease in most states, and not everyone who develops the flu seeks care or gets tested, according to the Centers for Disease Control and Prevention (CDC). Instead, the agency develops estimates based on rates of laboratory-confirmed, flu-associated hospitalizations.

In 2020, however, as the COVID-19 pandemic dominated the US, influenza cases were at an all-time low: Data from the CDC, supplied to JAMA, showed that out of 1.3 million specimens collected by labs between October 3, 2020, and July 24, 2021, only 2,136 were positive for influenza. Of those 2,136 influenza cases, there were only 748 flu-related deaths.

That's a huge difference from the rates of the 2019–2020 flu season. There were an estimated 35 million flu-related illnesses—that number included 16 million medical visits for the flu; 380,000 flu-related hospitalizations, and 20,000 deaths due to influenza.

Of course, those data were only from two specific years—and they show two very different ways the flu impacted the U.S. population. Here's what you need to know about how many people die from the flu each year on average, what infectious disease experts look for to gauge upcoming flu seasons, and how to protect yourself.

How Many People Die of the Flu Each Year on Average?

According to data collected by the CDC from 2010 to 2020, the agency estimates that the flu has caused 12,000 to 52,000 deaths annually. During that time, the flu also caused 9 million to 41 million illnesses and 140,000 to 710,000 hospitalizations. Globally, the World Health Organization (WHO) estimates that the flu kills 290,000 to 650,000 people per year.

Those numbers can vary so much from year to year because what we know as "the flu" isn't one specific thing—it's actually made up of different influenza strains that circulate.

"How many people die of the flu each year of the flu is definitely related to the strains that are circulating, how accurately researchers were able to predict what should go into the flu vaccine, and how many people are vaccinated," Anjali Mahoney, MD, Chief Medical Officer, at the Venice Family Clinic told Health.

Certain influenza strains can also be more severe than others. "Sometimes there are years where there are big genetic shifts, and we can see a very different virus," said Cassandra Pierre, MD, an Infectious Disease Physician at Boston Medical Center.

Robert L. Murphy, MD, a Professor of Infectious Diseases at Northwestern Medicine Feinberg School of Medicine, agreed, saying that the flu virus is always changing. "[Sometimes] it can be a nastier strain," Dr. Murphy said. "It goes up and down."

What Information Helps Predict the Severity of Upcoming Flu Seasons?

As indicated in an October 2017 article published in the American Journal of Epidemiology, the CDC uses the following factors called intensity threshold (IT) values to determine flu severity in general:

• Outpatient visit percentages for flu-like illnesses
• Flu-associated hospitalization rates
• Pneumonia or flu death percentages

Information related to these values plays a part in what the CDC calls flu forecasting. Flu forecasting is a process where other researchers beyond those within the agency submit data to help determine what preparations and preventive measures should be taken in regard to vaccinations, potential hospitalization influxes, healthcare provider and treatment distribution and placement, and community action guidance (e.g., organization closures).

Additionally, flu season severity predictions are based on data from other countries. For example, in 2021, Australia—which has its winter and flu season during summertime in the U.S.—didn't have a flu season. While that might have been good news for a less severe season in the U.S., it also spelled trouble for vaccine formulation.

"Usually when the powers that be are trying to figure out which strains to put in the vaccine, they are basing it on what circulated in the southern hemisphere during summer," James H. Conway, MD, a Pediatric Infectious Disease Specialist and Associate Director for Health Sciences at the Global Health Institute of UW-Madison, told Health. "They didn't have any flu season, so the powers that be couldn't figure out prevalent flu strains."

The low numbers of flu cases of a previous year could also negatively impact the following year's flu season. With lower-than-usual rates of both flu vaccinations and flu cases, the U.S. population can be "relatively immunologically naive," Dr. Conway said—that means we may not have any leftover immunity from last flu season. Pair that with more people going out into public more often with lessening mask restrictions, and it could lead to a potentially more severe flu season.

How Can You Protect Yourself From the Flu?

The straightforward answer here is to get vaccinated as soon as possible. "The only protection people can get is getting vaccinated and being careful about respiratory viruses," Dr. Conway said.

The CDC recommends that everyone 6 months and older get a flu vaccine every year. It's the first and most important step that people can take to guard against the flu and its complications.

The flu can be harder to fight off for specific populations, such as infants and young children, older people, and people who are immunocompromised due to chronic illnesses such as HIV or cancer. It's especially important for these populations to get vaccinated, possibly with a high-dose flu shot, if approved by their healthcare provider.

Those recommendations put in place for protection against COVID-19 can also come in handy when preventing the flu virus. "Everybody masking during winter months could help a lot with preventing flu deaths," Dr. Conway said. "That's done pretty regularly in some areas of the world. That may be as much a part of our major protection as major vaccines."

In addition to that, Dr. Conway suggested that people remain vigilant about staying home from work and school when they're ill. Proper handwashing and disinfecting surfaces can help keep illnesses at bay as well.