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HomeYour HealthConditionsViral IllnessesKnow Your Risk for Serious Illness from COVID-19 Know Your Risk for Serious Illness from COVID-19 

Published on Nov 15, 2023

Authored by Pfizer Medical Team

What is COVID-19?What is COVID-19?

Coronavirus disease (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus. If you are infected with the virus, you will most likely experience mild to moderate respiratory illness.


The respiratory system is composed of organs that are involved in breathing. These organs include the nose, throat, larynx, trachea (windpipe), bronchi, and lungs.


You will likely recover without requiring treatment or medication. However, some people may become seriously ill and require medical attention. You are more likely to develop serious illness from COVID-19 if you are older or you have underlying medical conditions like:

•    Cardiovascular (heart) disease

•    Diabetes

•    Chronic respiratory (lung) disease

•    Cancer

This list is not exhaustive.

 COVID-19 and Pre-existing Medical Conditions

If you have one or more of the above medical conditions (risk factors) and you get COVID-19, you may be more likely to:

Did you know?About 1 in 5 (20%) people worldwide have at least one underlying condition that puts them at high-risk of becoming seriously ill from COVID-19.1 COVID-19 and Pre-existing Medical Conditions


COVID-19 and Age


COVID-19 and Type 1 or Type 2 Diabetes COVID-19 and Cancer COVID-19 and immunocompromised conditions/weakened immune systems





Symptoms and Testing

If you have been exposed to the virus that causes COVID-19, you may develop symptoms within 5 to 6 days after exposure. Symptoms may vary from mild symptoms, such as headache, fatigue, and cough, to very severe symptoms, such as difficulty breathing, and even death. COVID-19 symptoms may be similar to those you may have due to other infections, such as the flu.

If you have flu-like symptoms, it may be COVID-19 and not the flu. Get tested for COVID-19 as soon as possible if you develop symptoms. Find out more about other viral illnesses and how best to treat them by visiting A Guide to Common Cold & Winter Viruses: What It Is, Symptoms & Treatments

Symptoms can include, but are not limited to:

  • Sore throat

  • Loss of smell or taste

  • Shortness of breath or difficulty breathing

  • Fatigue

  • Fever or chills

  • Congestion or runny nose

  • Diarrhoea

  • Nausea or vomiting

  • Muscle or body aches

  • Cough

  • Headache

What to do if you test positive? 

Although this article is not intended to provide specific advice to any individual, here are some important things to be aware of:

  • If your test result is positive for COVID-19, do not delay. Speak to or notify your healthcare provider as soon as possible, even if your symptoms are mild.
  • If you have difficulty breathing, seek immediate medical attention.
  • Your healthcare provider can tell you about treatment options for COVID-19 and if one is appropriate for you. Your healthcare provider can also tell you about appropriate self-care.
  • These treatments must be started within days (generally 5-7 days) after you start developing symptoms. This is why it is so important to contact your healthcare provider as soon as possible.

Click here to check if you're eligible for COVID-19 antiviral medicines

If you think you have been exposed to COVID-19 or have developed symptoms, get tested for COVID-19 as soon as possible.




  1. Clark, A., Jit, M., Warren-Gash, C., Guthrie, B., Wang, H. H. X., Mercer, S. W., Sanderson, C., McKee, M., Troeger, C., Ong, K. I., Checchi, F., Perel, P., Joseph, S., Gibbs, H. P., Banerjee, A., & Eggo, R. M. (2020). How many are at increased risk of severe COVID-19 disease? rapid global, regional and national estimates for 2020. The Lancet Global Health, 1003–1017. 

  2. Underlying medical conditions associated with higher risk for severe COVID-19: Information for Healthcare professionals. Centers for Disease Control and Prevention. (2022, February 15). Retrieved May 20, 2022, from

  3. Bae, S. A., Kim, S. R., Kim, M.-N., Shim, W. J., & Park, S.-M. (2021). Impact of cardiovascular disease and risk factors on fatal outcomes in patients with covid-19 according to age: A systematic review and meta-analysis. BMJ Journals, 107, 373–380.

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