Seroprevalence of Severe Acute Respiratory Syndrome Coronavirus 2-Specific Antibodies in Australia After the First Epidemic Wave in 2020: A National Survey

Kaitlyn M Vette; Dorothy A Machalek; Heather F Gidding; Suellen Nicholson; Matthew V N O'Sullivan; John B Carlin; Marnie Downes; Lucy Armstrong; Frank H Beard; Dominic E Dwyer; Robert Gibb; Iain B Gosbell; Alexandra J Hendry; Geoff Higgins; Rena Hirani; Linda Hueston; David O Irving; Helen E Quinn; Hannah Shilling; David Smith; John M Kaldor; Kristine Macartney

doi:10.1093/ofid/ofac002

Seroprevalence of Severe Acute Respiratory Syndrome Coronavirus 2-Specific Antibodies in Australia After the First Epidemic Wave in 2020: A National Survey

Open Forum Infect Dis. 2022 Jan 31;9(3):ofac002. doi: 10.1093/ofid/ofac002. eCollection 2022 Mar.

Authors

Kaitlyn M Vette¹, Dorothy A Machalek^{2

3}, Heather F Gidding^{1

4

5}, Suellen Nicholson⁶, Matthew V N O'Sullivan⁷, John B Carlin^{8

9}, Marnie Downes⁸, Lucy Armstrong¹, Frank H Beard^{1

10}, Dominic E Dwyer⁷, Robert Gibb¹¹, Iain B Gosbell^{12

13}, Alexandra J Hendry¹, Geoff Higgins¹⁴, Rena Hirani¹², Linda Hueston^{7

15}, David O Irving^{12

16}, Helen E Quinn^{1

10}, Hannah Shilling³, David Smith¹⁷, John M Kaldor², Kristine Macartney^{1

10}

Affiliations

¹ National Centre for Immunisation Research and Surveillance, Sydney, Australia.
² The Kirby Institute, University of New South Wales, Sydney, Australia.
³ Centre for Women's Infectious Diseases, The Royal Women's Hospital Melbourne, Melbourne, Australia.
⁴ University of Sydney Northern Clinical School, Sydney, Australia.
⁵ Women and Babies Research, Kolling Institute, Northern Sydney Local Health District, Sydney, Australia.
⁶ Victorian Infectious Diseases Reference Laboratory, The Royal Melbourne Hospital, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia.
⁷ Centre for Infectious Diseases and Microbiology, New South Wales Health Pathology - Institute for Clinical Pathology and Medical Research, Sydney, Australia.
⁸ Murdoch Children's Research Institute, Melbourne, Australia.
⁹ Department of Paediatrics and School of Population and Global Health, University of Melbourne, Melbourne, Australia.
¹⁰ University of Sydney, Sydney, Australia.
¹¹ Pathology Queensland, Brisbane, Australia.
¹² Clinical Services and Research, Australian Red Cross Lifeblood, Sydney, Australia.
¹³ School of Medicine, Western Sydney University, Sydney, Australia.
¹⁴ South Australia Pathology, Adelaide, Australia.
¹⁵ Menzies Health Institute Queensland, Griffith University, Brisbane, Australia.
¹⁶ Faculty of Health, University of Technology Sydney, Sydney, Australia.
¹⁷ PathWest Laboratory Medicine Western Australia, Perth, Australia.

Abstract

Background: As of mid-2021, Australia's only nationwide coronavirus disease 2019 (COVID-19) epidemic occurred in the first 6 months of the pandemic. Subsequently, there has been limited transmission in most states and territories. Understanding community spread during the first wave was hampered by initial limitations on testing and surveillance. To characterize the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibody seroprevalence generated during this time, we undertook Australia's largest national SARS-CoV-2 serosurvey.

Methods: Between June 19 and August 6, 2020, residual specimens were sampled from people undergoing general pathology testing (all ages), women attending antenatal screening (20-39 years), and blood donors (20-69 years) based on the Australian population's age and geographic distributions. Specimens were tested by Wantai total SARS-CoV-2-antibody assay. Seroprevalence estimates adjusted for test performance were produced. The SARS-CoV-2 antibody-positive specimens were characterized with microneutralization assays.

Results: Of 11 317 specimens (5132 general pathology; 2972 antenatal; 3213 blood-donors), 71 were positive for SARS-CoV-2-specific antibodies. Seroprevalence estimates were 0.47% (95% credible interval [CrI], 0.04%-0.89%), 0.25% (CrI, 0.03%-0.54%), and 0.23% (CrI, 0.04%-0.54%), respectively. No seropositive specimens had neutralizing antibodies.

Conclusions: Australia's seroprevalence was extremely low (<0.5%) after the only national COVID-19 wave thus far. These data and the subsequent limited community transmission highlight the population's naivety to SARS-CoV-2 and the urgency of increasing vaccine-derived protection.

Keywords: Australia; COVID-19; SARS-CoV-2; seroprevalence; serosurvey.