Last updated: 21 February 2020

Confirmed case

A person who tests positive to a validated specific SARS-CoV-2 nucleic acid test or has the virus identified by electron microscopy or viral culture, at a reference laboratory.

Suspect case

If the patient satisfies epidemiological and clinical criteria, they are classified as a suspect case.

Epidemiological criteria

• Travel to (including transit through) mainland China in the 14 days before the onset of illness.
  or
• Close or casual contact (see close and casual contact definitions below) in the 14 days before illness onset with a confirmed case of COVID-19.

Clinical criteria

• Fever
  or
• Acute respiratory infection (e.g. shortness of breath or cough) with or without fever.

Person under investigation

It is recommended that clinicians should consider testing people with a clinically compatible illness who travelled to any of the following countries in the 14 days before onset of symptoms:

• Hong Kong
• Indonesia
• Japan
• Singapore
• Thailand

This list is based on the volume of travel between those countries, Australia and China, and/or the current epidemiology of COVID-19; however, the risk of COVID-19 in these countries is currently thought to be low. clinical and public health judgement should be applied. The recommendation does not apply to passengers who have only been in transit through an airport in these countries.

Note: if a clinician determines that a person under investigation should be tested then that person must be managed as a suspect case until COVID-19 is confirmed or excluded as the cause of illness.

Rationale for current case definitions

The case definitions are based on what is currently known about the clinical and epidemiological profile of cases of COVID-19 presenting to date both in Australia and internationally. Health authorities are constantly monitoring the spectrum of clinical symptoms as cases arise, and, if there are any significant shifts, they will be reflected in the above definitions in future versions of this document. The same monitoring and revision applies for epidemiological criteria as new areas of varying risk emerge outside mainland China.

The 14 day period is based upon what is currently known to be the upper time limit of the incubation period. As more precise information about the incubation period emerges, this will be reviewed.

Close contact definition^*

A close contact is defined as requiring:

• greater than 15 minutes face-to-face contact in any setting with a confirmed case in the period extending from 24 hours before onset of symptoms in the confirmed case, or
• sharing of a closed space with a confirmed case for a prolonged period (e.g. more than 2 hours) in the period extending from 24 hours before onset of symptoms in the confirmed 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 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.
• All crew-members on an aircraft who worked in the same cabin area as a confirmed case of COVID-19. If a 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.

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

Casual contact definition

Casual contact is defined as any person having less than 15 minutes face-to-face contact with a symptomatic confirmed case in any setting, or sharing a closed space with a symptomatic confirmed case for less than 2 hours. This will include healthcare workers, other patients, or visitors who were in the same closed healthcare space as a case, but for shorter periods than those required for a close contact. Other closed settings might include schools or offices.

Note that healthcare workers and other contacts who have taken recommended infection control precautions, including the use of full PPE, while caring for a symptomatic confirmed COVID-19 case are not considered to be close contacts. However, these people should be advised to self-monitor and if they develop symptoms consistent with COVID-19 infection they should isolate themselves and notify their public health unit or staff health unit so they can be tested and managed as a suspected COVID-19 case.

Other casual contacts may include:

• extended family groups, e.g. in an Aboriginal community
• aircraft passengers who were not seated nearby a symptomatic confirmed case or a crewmember who did not work in the same cabin area as a symptomatic confirmed case (see close contact definition).

Notes

Where resources permit, more active contact tracing may be extended to other persons who have had casual contact (as defined above), particularly in school, office, or other closed settings. In these circumstances, the size of the room/space and degree of separation of the case from others should be considered in identifying contacts.

On 17 February 2020, CDNA agreed that due to the ongoing transmission of COVID-19 on the Diamond Princess, all passengers and crew on board​ the Diamond Princess cruise (which departed Yokohama on 20 January 2020 returning on 04 February 2020) are deemed close contacts and to be managed as such for up to 14 days from their departure from the ship.​​