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By the numbers: Everything you need to know about the flu shot, flu virus, and staying healthy during flu season

Flu shot statistics | Transmission | Flu statistics | Annual burden | Flu season

The flu, by definition, is a contagious respiratory illness caused by influenza viruses that infect the nose, throat, and sometimes the lungs. The flu, by reputation, is awful and can ruin your season. For anyone who hasn’t had it, though: The flu causes mild to severe symptoms in those infected, including, but not limited to: fever (or feeling feverish/chilled), cough, sore throat, runny or stuffy nose, muscle or body aches, headaches, fatigue, and even vomiting or diarrhea. It can cause mild to severe illness, and complications can lead to hospitalization or death particularly in high-risk groups. 

The flu virus is so common that the number of people infected each influenza season can only be estimated, not determined for certain. The Centers for Disease Control and Prevention (CDC) annually estimates the impact of the flu on the U.S. population, and preliminarily for the 2019-2020 flu season they’ve estimated there were 38 million cases, 18 million sought care from their healthcare provider, 400,000 were hospitalized, and 22,000 died with influenza. 

We collected flu statistics and facts from the CDC and other public health organizations to show the impact of flu season—and the power of the flu shot for avoiding the seasonal influenza virus.

RELATED: Immunization and vaccination statistics

Flu shot statistics

Experts agree that the best way to prevent the flu is by getting a flu vaccine each year. The flu shot is a vaccine that contains weakened or deactivated flu viruses, which allows your body’s immune system to learn to fight the virus before you come into contact with the live (and harmful) virus during flu season. Plus, if you get the flu shot and do still catch the flu, it will help lessen the severity and shorten the duration of symptoms. Take a stab at these flu shot facts:

  • It takes 2 weeks to develop antibodies after getting an influenza vaccination. 
  • It’s recommended that you start getting flu shots at 6 months.
  • The flu shot reduces your chances of getting the flu by 40%-60%.
  • 155.3 million doses of the influenza vaccine were shipped in the 2017-2018 season.
  • A flu shot will protect you against 3-4 flu strains.

More flu facts: 7 myths about the flu shot

Infographic describing the flu shot numbers

Flu transmission

Catching the flu is easier than one might want to believe. People infected with the flu can spread it to others up to about 6 feet away through airborne droplets that are exchanged when people who have the flu cough, sneeze, or talk. After becoming infected, those infected with the flu are most contagious in the first three to four days after their illness begins, but the virus can be spread before those who are infected experience any symptoms at all. Staying flu-free requires lots of handwashing, hydration, and preventive measures (like a flu shot). Here’s how you catch and keep the flu virus:

  • 24 hours—how long you can infect others before you have flu symptoms
  • 5-7 days—the length of time after getting sick that you can still pass infection
  • 2 days—the time between when you’re exposed and when you show symptoms

RELATED: Coronavirus (COVID-19) vs. the flu vs. a cold

Chart describing length of flu duration

Flu statistics

The reason you hear so much about the flu each year is because it’s incredibly common: Each year, 5% to 20% of the U.S. population will get the flu on average. A recent study found that adults get the flu twice per decade on average, but children are infected once every other year on average. There have been 9.3 to 45 million cases of the flu each year since 2010 according to the CDC. And the effects are serious. An estimated 140,000 to 810,000 Americans are hospitalized each year because of complications from the flu illness. And as for flu death statistics, 12,000 to 61,000 people have died each year from flu-related causes in the U.S over the past decade.

Infographic describing the flu deaths and hospitalization numbers

The cost of the flu

 Aside from the money (and time) lost when the flu sidelines you from work and play, the flu is very costly. In previous years, the U.S. has spent $1.3 billion on stockpiling oseltamivir (Tamiflu)—which adds up to 65 million dosages—to help treat diagnosed cases of the flu. On average, patients who start taking Tamiflu (Tamiflu details) within 48 hours of getting sick will recover one day faster than patients who do not take anything, according to Margaret Dayhoff-Brannigan, Ph.D., a patient network project manager at the National Center for Health Research. Every year, the flu has a very real cost:

  • 17 million work days are missed per year because of the flu
  • $7 billion—the estimated cost of sick days and lost productivity
  • $10 billion—spent on hospitalization and medical visits related to the flu
  • 3-5 days—the average number of school days children who contract the flu will miss

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RELATED: How to get a free flu shot

Infographic describing the economic impact of the flu in the U.S.

Flu season

You can come down with the flu at any time. Seasonal flu viruses are detected year-round in the United States, but flu viruses are most common during the fall and winter—giving us the concept of “flu season.” Cases of the flu often begin to rise in October, and flu activity peaks between December and February. 

RELATED: Flu season 2020—Why the flu shot is more important than ever

Infographic describing the flu season peaks in the U.S.