Wed, 11/11/2020 | News

Antibody study confirms low levels of infection in Sydney during the first COVID-19 wave 

Australia’s first population-level antibody study designed to shed light on how many people have contracted COVID-19 confirms that only a very small proportion – less than one percent – of Sydneysiders had been infected by the SARS-CoV-2 virus after the first epidemic wave. 

Experts say the findings show the success of measures taken to date in NSW to control the virus’s spread – but also the importance of people being vigilant and continuing to come forward for testing, given that the vast majority of people remain vulnerable to the infection. 

The study involved analyses of more than 5,330 de-identified blood samples from three different groups of people. If the results are extrapolated to Sydney’s five-million-strong population, it would suggest only one in 670 (or 7,450) of the city’s residents had been infected during the first wave in Sydney. While this is 3.5 times as high as the 2,118 COVID-19 cases detected and officially notified at the time, it represents a much lower level of community infection, and a lower ratio of undetected to detected infections, than seen in many international studies.

The study was co-led by NCIRS, the Kirby Institute at UNSW, and NSW Health Pathology’s Institute of Clinical Pathology and Medical Research (ICPMR). It was conducted in collaboration with Australian Red Cross Lifeblood and public and private diagnostic laboratories across Sydney, with support from the NSW Ministry of Health.

Read the full media release

Read the full study on MJA website

Declaration: This study was funded by the NSW Ministry of Health. The authors declare no competing interests. 

For further information and interviews with Professor Kristine Macartney and Associate Professor Heather Gidding, please email: