Learn About COVID-19

Understand what COVID-19 is, how it affects your body and people who are at higher risk for severe illness.

What Is COVID-19?

COVID-19, short for COronaVIrus Disease 2019, is a respiratory illness caused by a novel coronavirus named SARS-CoV-2 first detected in China in late 2019. By January 2020, with the spread of coronavirus disease to over 100 other locations, including the U.S., the World Health Organization (WHO) officially declared the outbreak a public health emergency and later, a pandemic. Only months later, confirmed cases of COVID-19 were recorded in almost every country around the world. Vaccines are now widely available to help protect against severe illness from COVID-19.

How It Affects Your Body

The lungs are the first body organ affected. In the early days of an infection, the novel coronavirus rapidly invades cells in our respiratory system, attacking the epithelial cells lining the airways—that catch and clear out things like pollen and viruses—flooding your airways with debris and fluids.

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Infectious respiratory diseases such as influenza, COVID-19, and pertussis spread from person to person. Learn how your body fights back against these pathogens and some of the common side effects that you may experience as your immune system attacks. Support for this educational program provided by Genentech.

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People who become sick with COVID-19 may experience mild to severe disease, or in many cases be asymptomatic (have no symptoms). COVID-19 symptoms, such as cough and shortness of breath, can come on suddenly. Severe illness may cause several complications that require medical intervention, including:

COVID-19 can be fatal for anyone, though the greatest percentage of individuals who die are over the age of 65 or are living with a chronic disease as listed at the bottom of the page. The best protection is to be up to date with your COVID-19 vaccines. If you test positive for COVID-19 and are at high risk for severe illness, there are treatments available to you.

Some individuals, even those with mild illness that did not require hospitalization, experience prolonged or new symptoms post-infection. Learn more about post-COVID long term symptoms.

People at Higher Risk for Severe Illness

Anyone can have mild to severe symptoms from COVID-19, and some people are asymptomatic (have no symptoms). There are some individuals who are at higher risk for severe illness, meaning they may end up needing to be hospitalized, put in the intensive care unit, need a ventilator to help them breathe or they may even die. 

Based on current information:

  • Adults over age 50 are at higher risk. Risk increases as you age so the older you are, the higher your risk with the greatest threat being to individuals over the age of 85 years old
  • People of all ages with underlying medical conditions, particularly if not well controlled, including:
    • People with chronic lung diseases including:
          • Chronic obstructive pulmonary disease (COPD), including emphysema and chronic bronchitis
          • Asthma that is moderate to severe
          • Bronchiectasis
          • Having damaged or scarred lung tissue such as interstitial lung disease, including idiopathic pulmonary fibrosis
          • Cystic fibrosis
          • Pulmonary hypertension
          • Tuberculosis
    • People who are immunocompromised from solid organ transplantation.
    • People living with a current cancer diagnosis, including lung cancer. Having a history of cancer may increase your risk as well.
    • People who are a current or former smoker
    • People who are overweight (body mass index [BMI] of 25 or higher), with obesity (body mass index [BMI] of 30 or higher) and especially severe obesity (BMI of 40 or higher)
  • Other medical conditions including serious heart conditions, type 1 or 2 diabetes, Down syndrome, neurological conditions such as dementia, mood disorders such as depression or schizophrenia, HIV infection, having a weakened immune system, chronic liver disease, have cerebrovascular disease, substance use disorders (including alcohol, opioids or cocaine use) and people with chronic kidney disease.
  • People who are pregnant or recently pregnant (within the last 42 days)

Children have been less affected by severe illness from COVID-19 than adults, though they can also experience severe symptoms up to and including death. Children with underlying medical conditions are at increased risk for severe illness. Learn more about COVID-19 and kids. 

Follow along for COVID-19 updates from the Centers for Disease Control and Prevention (CDC).
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Our Lung HelpLine is available to answer your questions about COVID-19. Contact our Lung HelpLine by calling 1-800-LUNGUSA or submitting a question online.
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Reviewed and approved by the American Lung Association Scientific and Medical Editorial Review Panel.

Page last updated: May 4, 2023

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