Eligibility Criteria for Respiratory Virus Testing: At Risk Ambulatory/Emergency Department Patients

Consistent with O. Reg. 671/92 of the French Language Services Act, test ordering and instructions on this page is only available in English because it is scientific or technical in nature and is for use only by qualified health care providers and not by members of the public.

This page provides respiratory virus testing eligibility criteria for ambulatory and emergency department patients who are at risk of severe disease or outcomes and whose treatment decisions may be impacted by test results.

For information on ordering respiratory virus testing from Public Health Ontario’s (PHO) laboratory, as well as additional patient eligibility criteria for respiratory virus testing, please refer to the Respiratory Virus (including influenza) test instructions.

The following lists outline ambulatory and emergency department patients eligible for respiratory virus testing at PHO’s laboratory:

Groups at Higher Risk and Underlying Medical Conditions for Severe Outcomes of Covid-191

Includes individuals from one or more of the following categories:

  1. 60 years of age or older
  2. 18 years of age or older and are immunocompromised
  3. 18 to 59 years of age and at a higher risk of severe COVID-19 including having:
    • inadequate immunity against COVID-19 from:
      • have not received a full primary series of a COVID-19 vaccine
      • have received a full primary series but have not received additional COVID-19 vaccine or have not had a COVID-19 infection within the past 6 months            
    • one or more underlying medical condition2:
      • cancer
      • cerebrovascular disease
      • chronic kidney disease
      • chronic liver diseases (limited to: cirrhosis, non-alcoholic fatty liver disease, alcoholic liver disease, and autoimmune hepatitis)
      • chronic lung diseases (limited to: bronchiectasis, chronic obstructive pulmonary disease, interstitial lung disease, pulmonary hypertension, pulmonary embolism)
      • cystic fibrosis
      • diabetes mellitus, type 1 and type 2
      • disabilities (e.g. Down syndrome, learning, intellectual, or developmental disabilities; ADHD; cerebral palsy; congenital disabilities; spinal cord injuries)
      • heart conditions (e.g., cardiomyopathies, coronary artery disease, heart failure, etc.)
      • HIV infection
      • mental health disorders (limited to: mood disorders, including depression; schizophrenia spectrum disorders)
      • obesity
      • pregnancy and recent pregnancy
      • primary immunodeficiency diseases
      • smoking, current or former
      • Solid organ or blood stem cell transplant
      • tuberculosis
      • use of corticosteroids or other immunosuppressive medication

Groups at Higher Risk for Severe Outcomes of Influenza3

Includes adults and children with influenza-like illness who:

  1. Have severe, complicated or progressive illness.
  2. Are at higher risk of complications of influenza, which include the following age groups, chronic medical conditions, and persons:
    • asthma and other chronic pulmonary disease, including asthma, bronchopulmonary dysplasia, cystic fibrosis, chronic bronchitis, and emphysema
    • cardiovascular disease (excluding isolated hypertension; including congenital and acquired heart disease, such as congestive heart failure and symptomatic coronary artery disease)
    • renal disease
    • chronic liver disease
    • diabetes mellitus and other metabolic diseases
    • anemia and hemoglobinopathies, such as sickle cell disease
    • cancer, immunosuppression, or immunodeficiency due to disease (e.g., HIV infection, especially if CD4 is <200 × 106/L) or management of underlying condition (solid organ transplant or hematopoietic stem cell transplant recipients)
    • neurological disease and neurodevelopmental disorders that compromise handling of respiratory secretions (cognitive dysfunction; spinal cord injury; neuromuscular, neurovascular, neurodegenerative, and seizure disorders; cerebral palsy; metabolic disorders)
    • children aged younger than 5 years (note: the risk of hospitalization is further increased among those aged younger than 2 years
    • individuals aged 65 years or older
    • people of any age who are residents of nursing homes or other chronic care facilities
    • pregnancy and up to 4 weeks postpartum regardless of how the pregnancy ended  (Note: the risk of influenza-related hospitalization increases with length of gestation (i.e., it is higher in the third trimester than in the second)
    • obesity with a BMI ≥40 or a BMI >3 z-scores above the mean for age and gender
    • children and adolescents aged younger than 18 years undergoing treatment for long periods with acetylsalicylic acid because of the potential increase in Reye’s syndrome associated with influenza
    • Indigenous peoples


  1. Ontario. Ministry of Health. Bulletin 230906 — update: COVID‑19 antiviral treatments and testing [Internet]. Toronto, ON: King’s Printer for Ontario; 2023 [cited 2024 Jan 9]. Antiviral treatments for COVID-19. Available from: https://www.ontario.ca/document/ohip-infobulletins-2023/bulletin-230906-update-covid-19-antiviral-treatments-and-testing
  2. Public Health Agency of Canada. People who are at risk of more severe disease or outcomes from COVID-19 [Internet]. Ottawa, ON: Government of Canada; 2022 [cited 2023 Jan 9]. Available from: https://www.canada.ca/en/public-health/services/publications/diseases-conditions/people-high-risk-for-severe-illness-covid-19.html
  3. Aoki FY, Allen UD, Mubareka S, Papenburg J, Stiver HG, Evans GA. Use of antiviral drugs for seasonal influenza: Foundation document for practitioners—update 2019. J Assoc Med Microbiol Infect Dis Canada. 2019;4(2):60-82. Available from: https://doi.org/10.3138/jammi.2019.02.08
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Published 15 Jan 2024