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Risk Factors for Severe COVID-19 Disease

Current information suggests that older people and those with chronic health conditions are at higher risk of developing more severe illness or complications.

Last updated: December 10, 2021

Patients at higher risk for COVID-19 complications

  • Older people and those with chronic health conditions such as diabetes, heart disease and lung disease are at higher risk of developing more severe illness or complications from COVID-19. 
  • Most people with COVID-19 recover; however, people with chronic diseases are also at higher risk of death if they become ill. 
  • Some individuals are considered clinically extremely vulnerable and have been prioritized for immunization. 

Risk Factors

Age is by far the single most important risk factor for severe illness or complications from COVID-19 including mortality. 

Age is by far the strongest predictor of hospitalization and mortality based on available data. The risk of severe illness and complications increases with age. The table below provides a breakdown of relative risk of mortality by age cohort using provincial data for the period of September 1, 2020 to January 5, 2021.

The following risk factors are also associated with greater risk for severe illness: 

  • Cancer
  • Cardiovascular disease
  • cerebrovascular disease
  • Chronic kidney disease
  • Chronic respiratory disease (e.g. chronic obstructive pulmonary disease (COPD), asthma, pulmonary hypertension, bronchiectasis)
  • Diabetes 
  • Down syndrome
  • Hypertension
  • Immunosuppression and immunodeficiency
  • Intellectual and developmental disability
  • Obesity (BMI >30)
  • Organ Transplant
  • Pregnancy
  • Sickle cell disease
  • Substance use (e.g. injection drug use, problematic alcohol use)
  • Schizophrenia and psychotic disorders
Adults of any age with one or more underlying medical conditions or comorbidities are at increased risk for severe illness from COVID-19. Comorbidities associated with the greatest risk of severe illness, defined as having an adjusted risk ratio (aRR) above 2.5 based on provincial data and/or a mortality risk (hazard ratio) above 2.5 based on OpenSAFELY data, include those with chronic kidney disease with an eGFR < 30, down syndrome, and organ transplant. Other comorbidities associated with a greater risk of severe illness include cancer, cardiovascular disease, chronic respiratory disease, diabetes, gout, immunosuppression and immunodeficiency, obesity, pregnancy, and sickle cell disease. 

Factors associated with hospitalization status in multivariable Poisson regression analysis with robust error variance among confirmed cases, BC COVID-19 Cohort

  • Race, ethnicity, socio-economic factors and their intersection
  • Sex at birth
  • Other populations that warrant special consideration
  1. Velásquez García HA, Wilton J, Smolina K, et al. Mental Health and Substance Use Associated with Hospitalization among People with COVID-19: A Population-Based Cohort Study. Viruses. 2021;13(11):2196. Published 2021 Oct 31. doi:10.3390/v13112196
  2. Rapid Evidence Report: Risk Factors for Severe COVID-19 Outcomes, COVID-19 Scientific Advisory Group, Alberta Health Services, Nov 19, 2021.
  3. Underlying Medical Conditions Associated with Higher Risk for Severe COVID-19: Information for Healthcare Providers, Centers for Dease Control Oct 14, 2021.

Supporting patients

  • Get vaccinated with all recommended doses of COVID-19 vaccine.
  • Wash your hands often with soap and water for at least 20 seconds, or use an alcohol-based hand sanitizer containing at least 60% alcohol and avoid touching their face. 
  • Wear a mask when outside of your home, especially indoors, and even outdoors if you are within 2 metres of someone else for more time than just passing by.
  • Stay 2 metres away from others.
  • Avoid indoor crowded environments.
  • Avoid large gatherings and stay away from other people who are ill. 
  • For more information on the spread and prevention of COVID-19, refer to the How It Spreads page.
  • It is prudent to have at least a two-week supply of medications on hand.
  • The Public Health Agency of Canada has issued guidance for all Canadians on preparedness and COVID-19.
  • The BC College of Pharmacists has information about visiting pharmacies and accessing medication.
  • It’s important to ensure patients continue to receive medical care for chronic conditions.
  • ‎People with certain chronic conditions (particularly people on medications that suppress the immune system) may consider “protective self separation.” This means staying separate from other people as much as possible. 
  • For many people, staying at home for long periods will not be an option. 
  • If there is widespread local transmission of COVID-19, people with chronic conditions should consider reducing their exposure to large gatherings, particularly those where they will be in close contact with others. 

SOURCE: Risk Factors for Severe COVID-19 Disease ( )
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