Please note that some states and territories have implemented different criteria. Please see your state of territory department of health guidance for further confirmation.



The Communicable Diseases Network Australia (CDNA) National Guidelines for Public Health Units define confirmed, probable and suspected cases as:

Confirmed case

A person who:

i. tests positive to a validated specific SARS-CoV-2 nucleic acid test;

OR

ii. has the virus isolated in cell culture, with PCR confirmation using a validated method;

OR

iii. undergoes a seroconversion to or has a significant rise in SARS-CoV-2 neutralising or IgG antibody level (e.g. four-fold or greater rise in titre).1



Probable case

A person who has detection of SARS-CoV-2 neutralising or IgG antibody1 AND has had a compatible clinical illness AND meets one or more of the epidemiological criteria outlined in the suspect case definition (see below).

Suspect case

Clinical and public health judgement should be used in assessing if hospitalised patients with nonspecific signs of infection and patients who do not meet the clinical or epidemiological criteria should be considered suspect cases.​



A person who meets the following clinical AND epidemiological criteria:



Clinical Criteria:

Fever (≥38°C)2 or history of fever (e.g. night sweats, chills) OR acute respiratory infection (e.g. cough, shortness of breath, sore throat)4 OR loss of smell or loss of taste.



Epidemiological criteria:



In the 14 days prior to illness onset:

Close contact 5,6 (see Contact definition below) with a confirmed or probable case

(see Contact definition below) with a confirmed or probable case International

Passengers or crew who have travelled on a cruise ship

Healthcare, aged or residential care workers and staff with direct patient contact

People who have lived in or travelled through a geographically localised area with elevated risk of community transmission, as defined by public health authorities4



Notes:

1 Antibody detection must be by a validated assay and included in an external quality assurance program.

2 It is recommended that temperature is measured using a tympanic, oral or other thermometer proven to consistently and accurately represent peripheral body temperature.

3 If the person is a close contact of a probable case, at least one person in the chain of transmission must be a confirmed case.

4 Other reported symptoms of COVID-19 include: fatigue, loss of smell, loss of taste, runny nose, muscle pain, joint pain, diarrhoea, nausea/vomiting and loss of appetite. Clinical and public health judgement should be used to determine if individuals with sudden and unexplained onset of one or more of these other symptoms should be considered suspect cases.

5 Testing household contacts of confirmed or probable cases of COVID-19 may not be indicated where resources are constrained. These cases would be considered ‘probable cases’ (refer to definition above).

6 In certain high risk outbreak settings, PHU may consider testing asymptomatic contacts to inform management of the outbreak. For further information, refer to outbreak investigation and management in high-risk settings section of the guidelines

7 For further information on geographically localised areas with elevated risk of community transmission, refer to the Department of Health website.

A close contact is defined as requiring:

face-to-face contact in any setting with a confirmed or probable case, for greater than 15 minutes cumulative over the course of a week, in the period extending from 48 hours before onset of symptoms in the confirmed or probable case, or

sharing of a closed space with a confirmed or probable case for a prolonged period (e.g. more than 2 hours) in the period extending from 48 hours before onset of symptoms in the confirmed or probable case.

For the purposes of surveillance, a close contact includes a person meeting any of the following criteria:

Living in the same household or household-like setting (e.g. in a boarding school or hostel).

Direct contact with the body fluids or laboratory specimens of a case without recommended PPE or failure of PPE.

A person who spent 2 hours or longer in the same room (such as a GP or ED waiting room; a school classroom; communal room in an aged care facility). See Special situations for further information specific to aged care facilities and schools.

A person in the same hospital room when an aerosol generating procedure is undertaken on the case, without recommended PPE.

Aircraft passengers who were seated in the same row as the case, or in the two rows in front or two rows behind a confirmed COVID-19 case. Contact tracing of people who may have had close contact on long bus or train trips should also be attempted where possible, using similar seating/proximity criteria.

For aircraft crew exposed to a confirmed case, a case-by-case risk assessment should be conducted by the airline to identify which crew member(s) should be managed as close contacts. See Special situations and Appendix D of the guidelines for further information.

If an aircraft crew member is the COVID-19 case, contact tracing efforts should concentrate on passengers seated in the area where the crew member was working during the flight and all of the other members of the crew. A case by case risk assessment should be conducted to identify which passengers and crew members should be managed as close contacts. See Special situations and Appendix D of the guidelines for further information.

Close contacts on cruise ships can be difficult to identify, and a case-by-case risk assessment should be conducted to identify which passengers and crew should be managed as close contacts. See Special situations for further information.

Contact needs to have occurred within the period extending 48 hours before onset of symptoms in the case until the case is classified as no longer infectious by the treating team (usually 24 hours after the resolution of symptoms).



If the case is asymptomatic, see PCR positive tests in asymptomatic or pre-symptomatic persons section in the guidelines for information on determining the asymptomatic (or pre-symptomatic) case’s infectious period and to inform identification of contacts.



Note that: