Serological testing of blood donors to characterise the impact of COVID-19 in Melbourne, Australia, 2020

Dorothy A Machalek; Kaitlyn M Vette; Marnie Downes; John B Carlin; Suellen Nicholson; Rena Hirani; David O Irving; Iain B Gosbell; Heather F Gidding; Hannah Shilling; Eithandee Aung; Kristine Macartney; John M Kaldor

doi:10.1371/journal.pone.0265858

Serological testing of blood donors to characterise the impact of COVID-19 in Melbourne, Australia, 2020

PLoS One. 2022 Jul 6;17(7):e0265858. doi: 10.1371/journal.pone.0265858. eCollection 2022.

Authors

Dorothy A Machalek^{1

2}, Kaitlyn M Vette³, Marnie Downes⁴, John B Carlin^{4

5}, Suellen Nicholson⁶, Rena Hirani^{7

8}, David O Irving^{7

9}, Iain B Gosbell^{7

10}, Heather F Gidding^{3

11

12}, Hannah Shilling^{2

4}, Eithandee Aung^{1

2}, Kristine Macartney^{3

10}, John M Kaldor¹

Affiliations

¹ The Kirby Institute, University of New South Wales, Sydney, Australia.
² Centre for Women's Infectious Diseases, The Royal Women's Hospital, Melbourne, Australia.
³ National Centre for Immunisation Research and Surveillance, Sydney, Australia.
⁴ Murdoch Children's Research Institute, Melbourne, Australia.
⁵ Department of Paediatrics and School of Population and Global Health, University of Melbourne, Melbourne, Australia.
⁶ Victorian Infectious Diseases Reference Laboratory, The Royal Melbourne Hospital, The Peter Doherty Institute for Infection and Immunity, Melbourne, Australia.
⁷ Clinical Services and Research, Australian Red Cross Lifeblood, Sydney, Australia.
⁸ Department of Molecular Sciences, Macquarie University, Sydney, Australia.
⁹ Faculty of Health, University of Technology Sydney, Sydney, Australia.
¹⁰ School of Medicine, Western Sydney University, Sydney, Australia.
¹¹ Faculty of Medicine and Health, The University of Sydney Northern Clinical School, Sydney, Australia.
¹² Women and Babies Research, Kolling Institute, Northern Sydney Local Health District, Sydney, Australia.

Abstract

Rapidly identifying and isolating people with acute SARS-CoV-2 infection has been a core strategy to contain COVID-19 in Australia, but a proportion of infections go undetected. We estimated SARS-CoV-2 specific antibody prevalence (seroprevalence) among blood donors in metropolitan Melbourne following a COVID-19 outbreak in the city between June and September 2020. The aim was to determine the extent of infection spread and whether seroprevalence varied demographically in proportion to reported cases of infection. The design involved stratified sampling of residual specimens from blood donors (aged 20-69 years) in three postcode groups defined by low (<3 cases/1,000 population), medium (3-7 cases/1,000 population) and high (>7 cases/1,000 population) COVID-19 incidence based on case notification data. All specimens were tested using the Wantai SARS-CoV-2 total antibody assay. Seroprevalence was estimated with adjustment for test sensitivity and specificity for the Melbourne metropolitan blood donor and residential populations, using multilevel regression and poststratification. Overall, 4,799 specimens were collected between 23 November and 17 December 2020. Seroprevalence for blood donors was 0.87% (90% credible interval: 0.25-1.49%). The highest estimates, of 1.13% (0.25-2.15%) and 1.11% (0.28-1.95%), respectively, were observed among donors living in the lowest socioeconomic areas (Quintiles 1 and 2) and lowest at 0.69% (0.14-1.39%) among donors living in the highest socioeconomic areas (Quintile 5). When extrapolated to the Melbourne residential population, overall seroprevalence was 0.90% (0.26-1.51%), with estimates by demography groups similar to those for the blood donors. The results suggest a lack of extensive community transmission and good COVID-19 case ascertainment based on routine testing during Victoria's second epidemic wave. Residual blood donor samples provide a practical epidemiological tool for estimating seroprevalence and information on population patterns of infection, against which the effectiveness of ongoing responses to the pandemic can be assessed.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Antibodies, Viral
Blood Donors*
COVID-19* / epidemiology
Humans
SARS-CoV-2
Seroepidemiologic Studies

Substances

Antibodies, Viral

Grants and funding

The study was supported by the Victorian Government Department of Health, and Snow Medical Foundation (CT28701/G207593). The Australian Government funds Australian Red Cross Lifeblood to provide blood, blood products and services to the Australian community. The funders have no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.