Criteria

World Health Organization: case definitions[152]

Suspect case

  • A. Patients with acute respiratory illness (i.e., fever and at least one sign/symptom of respiratory disease such as cough or shortness of breath) AND a history of travel to or residence in a location reporting community transmission of COVID-19 during the 14 days prior to symptom onset; OR

  • B. Patients with any acute respiratory illness AND having been in contact with a confirmed or probable COVID-19 case in the last 14 days prior to symptom onset; OR

  • C. Patients with severe acute respiratory illness (i.e., fever and at least one sign/symptom of respiratory disease such as cough or shortness of breath) AND requiring hospitalisation AND in the absence of an alternative diagnosis that fully explains the clinical presentation. 

Probable case

  • A. Suspect case for whom testing for the COVID-19 virus is inconclusive (inconclusive being the result of the test reported by the laboratory); OR

  • B. Suspect case for whom testing could not be performed for any reason.

Confirmed case

  • Patients with laboratory confirmation of COVID-19 infection, irrespective of clinical signs and symptoms.

Definition of contact

  • A contact is a person who experienced any one of the following exposures during the 2 days before and the 14 days after the onset of symptoms of a probable or confirmed case:

    • Face-to-face contact with a probable or confirmed case within 1 metre (3 feet) and for more than 15 minutes

    • Direct physical contact with a probable or confirmed case

    • Direct care for a patient with probable or confirmed COVID-19 disease without using proper personal protective equipment

    • Other situations as indicated by local risk assessments. 

  • Note: for confirmed asymptomatic cases, the period of contact is measured as the 2 days before through the 14 days after the date on which the sample was taken that led to confirmation.

WHO: global surveillance for human infection with coronavirus disease (COVID-19) external link opens in a new window

Centers for Disease Control and Prevention: criteria to guide evaluation and laboratory testing for COVID-19[153]

Clinicians should use their judgement to determine whether a patient has signs and symptoms compatible with COVID-19 and whether the patient should be tested. Most patients with confirmed COVID-19 have developed fever and/or symptoms of acute respiratory illness (e.g., cough, difficulty breathing).

Priorities for testing

  • Priority 1

    • Hospitalised patients

    • Symptomatic healthcare workers 

  • Priority 2

    • Patients in long-term care facilities with symptoms

    • Patients 65 years of age and older with symptoms

    • Patients with underlying conditions with symptoms

    • First responders with symptoms

  • Priority 3

    • Critical infrastructure workers with symptoms

    • Individuals who do not meet any of the above categories with symptoms

    • Healthcare workers and first responders

    • Individuals with mild symptoms in communities experiencing high COVID-19 hospitalisations 

  • Non-priority

    • Individuals without symptoms

Other considerations that may guide testing are epidemiologic factors such as the occurrence of local community transmission of COVID-19 infections in a jurisdiction. Clinicians are strongly encouraged to test for other causes of respiratory illness, including infections such as influenza.

CDC: evaluating and testing persons for coronavirus disease 2019 (COVID-19) external link opens in a new window

CDC: priorities for testing patients with suspected COVID-19 infection external link opens in a new window

Infectious Diseases Society of America (IDSA): COVID-19 prioritization of diagnostic testing[154]

IDSA recommends a tiering system for prioritising patients given the current limited availability of near-patient or point-of-care testing. These recommendations will likely change as testing becomes more widely available.

Tier 1

  • Critically ill patients in the intensive care unit with unexplained viral pneumonia or respiratory failure, regardless of travel history or close contact with a suspected or confirmed COVID-19 patient.

  • Any person, including healthcare workers, with fever or signs/symptoms of a lower respiratory tract illness and close contact with a laboratory-confirmed COVID-19 patient within 14 days of symptom onset (including all residents of a long-term care facility that has a laboratory-confirmed COVID-19 case). 

  • Any person, including healthcare workers, with fever or signs/symptoms of a lower respiratory tract illness and a history of travel within 14 days of symptom onset to geographical regions where sustained community transmission has been identified.

  • Individuals with fever or signs/symptoms of a lower respiratory tract illness who also are immunosuppressed (including patients with HIV), are older, or have underlying chronic health conditions. 

  • Individuals with fever or signs/symptoms of a lower respiratory tract illness who are critical to pandemic response including healthcare workers, public health officials, and other essential leaders. 

Tier 2

  • Hospitalised (non-intensive care unit) patients and long-term care facility residents with unexplained fever and signs/symptoms of a lower respiratory tract illness. The number of confirmed COVID-19 cases in the community should be considered. 

  • As testing becomes more widely available, routine testing of hospitalised patients may be important for infection prevention and management at discharge. 

Tier 3

  • Patients in outpatient settings who meet the criteria for influenza testing (e.g., older people and/or those with underlying health conditions). Testing in pregnant women and symptomatic children with similar risk factors for complications is encouraged. The number of confirmed COVID-19 cases in the community should be considered.

Tier 4

  • Community surveillance as directed by public health and/or infectious diseases authorities.

IDSA: COVID-19 prioritization of diagnostic testing external link opens in a new window

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