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Asymptomatic COVID-19 or are we missing something?
Jazmin K Daniells1, Helen L MacCallum1, David N Durrheim1
1Hunter New England Population Health, NSW, Australia; School of Medicine and Public Health, University of Newcastle, NSW, Australia.
Communicable Diseases Intelligence (2018)
|July 10, 2020
Summary
Contact tracing for coronavirus disease 2019 (COVID-19) in the Northern Territory identified 493 close contacts. Four close contacts, including cruise ship passengers and household members, tested positive for COVID-19.
Area of Science:
- Public Health
- Infectious Disease Epidemiology
- Contact Tracing
Background:
- The Northern Territory (NT) reported 28 cases of coronavirus disease 2019 (COVID-19) between March 1 and April 30, 2020.
- Effective contact tracing is crucial for controlling infectious disease outbreaks.
Purpose of the Study:
- To describe the contact tracing process for COVID-19 cases in the NT.
- To determine the secondary infection rate among close contacts of COVID-19 cases in the NT.
Main Methods:
- The NT Centre for Disease Control (CDC) conducted contact tracing for all notified COVID-19 cases.
- Identified close contacts were monitored daily for 14 days for disease symptoms.
- Case ascertainment and secondary infection rates were calculated for different contact groups.
Main Results:
- 527 close contacts were identified; 493 were successfully contacted and 445 were located in the NT.
- Four close contacts (0.9% of 445) tested positive for COVID-19 after developing symptoms.
- Secondary infection rates were 4.3% for cruise ship passengers and 3.9% for household contacts; no infections occurred in aircraft passengers or healthcare workers.
Conclusions:
- Contact tracing in the NT successfully identified and monitored close contacts of COVID-19 cases.
- Cruise ship passengers and household contacts represented the highest risk groups for secondary COVID-19 transmission in this cohort.

