How Deadly Is the Flu?

Influenza, commonly known as "the flu," is a virus that affects millions of people in the United States each year. Most people recover after a short bout of illness. However, the Centers for Disease Control and Prevention (CDC) indicate that between 1999 and 2019, 1.8 of every 100,000 people in the U.S. who got the flu died from it.

The severity of the flu, and its subsequent impact, changes from year to year. Older people, babies younger than 6 months old, pregnant people, and people with certain underlying health conditions are at a higher risk of complications from the flu.

This article provides flu mortality rates and discusses the warning signs, risk factors, and treatments for the flu.

Sick woman sitting on sofa covered in blanket with cup of tea and laptop

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Annual Flu Deaths 

Annual flu deaths vary from year to year. Between 2010 and 2019, yearly flu deaths have been as low as 12,000 and as high as 52,000. A number of factors contribute to the variation, including:

  • Flu vaccination rates
  • Seasonal flu vaccine efficacy
  • Timing of the flu season
  • Characteristics of the virus

How It’s Spread 

When a person coughs, sneezes, or talks, they expel droplets from their bodies. The flu is spread when infected droplets land in the nose or mouth of someone who isn't sick. It's also possible to get the flu by touching an infected surface and then touching your eyes, nose, or mouth, but it's far less common.

If you've ever been outside when it's so cold that you can see your breath, this will help you visualize how the flu is spread. It typically appears as a concentrated cloud that travels about 6 feet from your body before it dissipates. The droplets are more concentrated closest to the body and become less concentrated as they move away.

This is why the CDC recommends that sick people stay home and not have contact with others—or maintain at least a 6 foot distance when in necessary contact—to reduce the risk of spread.

Flu Contagious Period

The flu can be spread one day before symptoms start and up to 5-7 days thereafter in people with a healthy immune system. It's most contagious in the first 3-4 days after the illness begins.

People with a weakened immune system or young children may be able to spread it longer, since their bodies are not as well-equipped to fight off a virus.

Asymptomatic Spread

It's possible for people who are asymptomatic, meaning they have no symptoms at all, to spread the flu.

When Is Influenza Fatal?

Although most people will recover from the flu within about two weeks or less, complications of the flu can cause influenza to become fatal. Complications of the flu include:

The flu can also make certain chronic medical conditions worse, leading to increased risk for complications and death.

Recognizing the warning signs of the flu will help you to know when it's time to seek medical treatment. The CDC provides the following warning signs of the flu in children and adults:

  • Difficulty breathing or shortness of breath
  • Persistent pain or pressure in the chest or abdomen
  • Persistent dizziness, confusion, or inability to be active
  • Seizures
  • Inability to urinate
  • Severe muscle pain, weakness, or unsteadiness
  • Fever or cough that improves and then returns or worsens
  • Worsening of existing chronic conditions

Young children may see these additional signs:

  • Bluish lips or face
  • Ribs pulling in with breath
  • Chest pain
  • Dehydration

Who’s at Risk?

People most at risk for flu complications include:

Talk to your healthcare provider about any concerns you have about your risk for the flu and what you can do to protect yourself.

Preparing for Flu Season

The influenza virus mutates (changes) each year. This evolving virus requires a new version of the vaccine each year to work against it.

Getting a flu vaccine is the most effective way to prepare yourself for flu season.

Benefits of Flu Vaccination

A 2021 study found that adults who had received the flu vaccine and were hospitalized for flu were 26% less likely to be admitted to an intensive care unit (ICU) than those who hadn't received the flu vaccine. The same study reported that people who were vaccinated and hospitalized for flu-related illness were 31% less likely to die from flu-related illness than those who were unvaccinated.

Additional steps to help you prepare for flu season include:

  • Avoid contact with people who are sick
  • Stay home if you are sick
  • Practice good hygiene by washing your hands regularly
  • Cover your mouth when you cough or sneeze
  • Regularly clean and disinfect commonly touched surfaces
  • Avoid touching your eyes, nose, and mouth

Verywell / Ellen Lindner

Flu Treatment

The flu can be treated at home with medications used to reduce fevers. You can also treat your flu symptoms by:

  • Staying properly hydrated
  • Getting lots of rest
  • Staying home from school or work for at least 24 hours after your fever has resolved

A healthcare provider may prescribe an antiviral drug to someone who is very sick or at a greater risk of complications from the flu. Antivirals are used to stop the virus from making copies of itself, thus reducing the severity and duration of the illness. These medications can reduce symptom duration by about a day, and are most effective when started within one to two days of illness onset.


Unfortunately, the flu can be deadly, especially for those in high-risk groups such as older adults and people with chronic health conditions. But in the majority of cases, the flu is not deadly. Understanding how the flu virus is spread is the first step in understanding how to protect yourself from it. Getting your annual flu vaccine is the best measure of protection. Adding in additional precautions such as regular hand washing and avoiding people who are sick will help to keep you safe and healthy.

A Word From Verywell 

It's valid to be scared of getting the flu and wondering what might happen if you do. Talk to your healthcare provider about your concerns, especially if you fall into a high risk category. Fortunately, you now know the major warning signs to look for and that early treatment within the first one or two days can treat the flu.

Frequently Asked Questions

  • Is the flu viral or bacterial?

    The flu is a type of virus. The most common influenza viruses in humans are known as "Influenza A" or "Influenza B" and they typically affect the upper respiratory system.

  • How deadly is the flu compared to COVID?

    In the 2019-2020 flu season, the flu took the lives of an estimated 20,000 people in the United States. Comparatively, there were 375,000 COVID deaths in the same population in 2020.

  • Do more annual flu deaths happen in the winter?

    Flu season is between October to April, but typically peaks between December and February. Annual flu deaths commonly occur during the winter season.

  • How do you know if you have the flu or COVID?

    Symptoms of the flu and COVID are very similar. The only way to know for sure whether you have the flu or COVID is to get tested.

11 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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  5. Centers for Disease Control and Prevention. Flu symptoms & complications.

  6. Centers for Disease Control and Prevention. Flu: what to do if you get sick.

  7. Centers for Disease Control and Prevention. People at higher risk of flu complications.

  8. Ferdinands JM, Thompson MG, Blanton L, Spencer S, Grant L, Fry AM. Does influenza vaccination attenuate the severity of breakthrough infections? a narrative review and recommendations for further research. Vaccine. 2021;39(28):3678-3695. doi:10.1016/j.vaccine.2021.05.011

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  11. CDC Morbidity and Mortality Weekly Report. Provisional mortality data - United States 2020.

By Teresa Maalouf, MPH
Teresa Maalouf is a public health professional with six years of experience in the field. She has worked in research, tobacco treatment, and infectious disease surveillance. Teresa is focused on presenting evidence-based health information in a way that is clear and approachable.