With the COVID-19 vaccination effort continuing and the infection rate declining, the nation might soon return to something like normal. But the US still contends with viruses like the seasonal flu annually. While much less deadly than the COVID-19 pandemic, the average flu season kills thousands of Americans each year, according to data from the Centers for Disease Control and Prevention (CDC).

When is the flu season?

The CDC determines the start and end of flu season by monitoring flu activity — illnesses, medical visits, and hospitalizations — through its influenza surveillance systems. Most seasons begin in October, peak between December and February, and continue through May. The 2019-2020 flu season was unusual in that flu activity began to decline in March. According to the CDC, this was “perhaps associated with community prevention measures for COVID-19.”

How many people die from the flu?

The CDC estimates that an average of 36,000 people died of the flu each year over the past decade. The worst recent flu season was 2017-2018, when 61,000 people died from the flu. Around 22,000 people died of the flu during the shorter 2019-2020 season — the second lowest death total in the past 10 years, after the 12,000 flu deaths in the 2011-2012 season.

Even accounting for the fact that the COVID-19 pandemic has lasted a year instead of eight months, it has taken an average of 36,000 more lives per month when compared to the 2017-2018 flu season.

About 61,000 people died in the 2017-2018 flu season, the worst in the past decade.

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Since not everyone sick with the flu visits a doctor, and not all flu deaths occur in the hospital, the CDC uses mathematical modeling based on its surveillance data to estimate the total number of illnesses and deaths. This model considers factors like testing frequency, the likelihood of seeking medical care, and underreporting on death certificates. The flu can lead to death by pneumonia, congestive heart failure, or chronic obstructive pulmonary disease — in which case flu testing may occur too late or not at all. According to the CDC, “only counting deaths where influenza was recorded on a death certificate would be a gross underestimation of influenza’s true impact.” For comparison, CDC death certificate data shows that just 5,894 people died of the flu in 2019.

Still, state-level unadjusted death certificate data can help show how flu mortality rates vary across the nation.

Vermont, Oregon, and Idaho had the highest flu death rates in 2019.

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In 2017, the flu hit several states in the Northwest especially hard, while Missouri, Kansas, and West Virginia faced the highest death rates in 2018.

How does flu risk vary by age?

As with COVID-19, most flu deaths occur among Americans aged 65 or older. As of March 19, almost 81% of people who have died from COVID-19 have been in this age group. This is within the range of a normal flu season, with older Americans making up 62% of flu deaths in the 2019-2020 season, 75% in the 2018-2019 season, and 83% in the 2017-2018 season.

Younger Americans tend to fall ill with the flu more often.

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Children younger than five are likeliest to get the flu, as well as to see a doctor about it, followed by older children and adults — the CDC notes that adults aged 18 to 64 tend to have lower rates of vaccination. But older Americans, despite being the least likely to get sick, are the most likely to be hospitalized and die.

Despite being the least likely to get the flu, Americans 65 and older are the most likely to die from it.

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In total, about 0.8% of all Americans 65 and older have died from COVID-19, while 0.03% of people in that age group died in 2019-2020 flu season and 0.1% in the 2017-2018 season.

How much does vaccination protect from the flu?

Vaccinations prevented an estimated 6,300 deaths in the 2019-2020 flu season. In the past decade, they have prevented as few as 3,500 deaths in the 2018-2019 season and as many as 12,000 deaths in the 2013-2014 season. According to mandatory reporting, 80% of children who die from the flu are unvaccinated.

To learn more, read about how many Americans get flu shots or track COVID-19 vaccine progress, cases, and deaths.