Serology study of healthcare workers following a hospital-based outbreak of COVID-19 in North West Tasmania, Australia, 2020

Michelle McPherson; Nicola Stephens; Kylie J Smith; M Therese Marfori; Meru Sheel; Louise Cooley; Belinda McEwan; Mark Veitch; Fay H Johnston

doi:10.33321/cdi.2023.47.6

Serology study of healthcare workers following a hospital-based outbreak of COVID-19 in North West Tasmania, Australia, 2020

Commun Dis Intell (2018). 2023 Jan 19:47. doi: 10.33321/cdi.2023.47.6.

Authors

Michelle McPherson^{1

2}, Nicola Stephens^{1

2}, Kylie J Smith^{2

3}, M Therese Marfori^{2

3}, Meru Sheel⁴, Louise Cooley, Belinda McEwan⁵, Mark Veitch², Fay H Johnston^{2

3}

Affiliations

¹ Tasmanian School of Medicine, University of Tasmania, Hobart, Tasmania, Australia.
² Public Health Services, Department of Health, Tasmania, Australia.
³ Menzies Institute for Medical Research, University of Tasmania, Tasmania, Australia.
⁴ Sydney School of Public Health, Faculty of Medicine and Health, University of Sydney, New South Wales Australia.
⁵ Tasmanian Department of Health, Tasmania, Australia.

PMID: 36654505
DOI: 10.33321/cdi.2023.47.6

Abstract

Introduction: Healthcare facilities are high-risk settings for coronavirus disease 2019 (COVID-19) transmission. Early in the COVID-19 pandemic, the first large healthcare-associated outbreak within Australia occurred in Tasmania. Several operational research studies were conducted amongst workers from the implicated hospital campus, to learn more about COVID-19 transmission.

Methods: Healthcare workers (HCWs) from the implicated hospital campus were invited to complete an online survey and participate in a serology study. Blood samples for serological testing were collected at approximately 12 weeks (round one) and eight months (round two) after the outbreak. A descriptive analysis was conducted of participant characteristics, serology results, and longevity of antibodies.

Results: There were 261 HCWs in round one, of whom 44 (17%) were polymerase chain reaction (PCR) confirmed outbreak cases; 129 of the 261 (49%) participated in round two, of whom 34 (27%) were outbreak cases. The prevalence of positive antibodies at round one was 15% (n = 38) and at round two was 12% (n = 15). There were 15 participants (12%) who were seropositive in both rounds, with a further 9% (n = 12) of round two participants having equivocal results after previously being seropositive. Six HCWs not identified as cases during the outbreak were seropositive in round one, with three still seropositive in round two. Of those who participated in both rounds, 68% (n = 88) were seronegative at both time points.

Discussion: Our findings demonstrate that serological testing after this large healthcare-associated COVID-19 outbreak complemented the findings of earlier diagnostic testing, with evidence of additional infections to those diagnosed when use of PCR testing had been restricted. The results also provide evidence of persisting SARS-CoV-2 antibody response eight months after an outbreak in an unvaccinated population. The high proportion of HCWs who remained seronegative is consistent with low community transmission in Tasmania after this outbreak.

Keywords: COVID-19; healthcare workers; hospital-based outbreak; seroprevalence.

MeSH terms

Australia / epidemiology
COVID-19* / epidemiology
Disease Outbreaks
Health Personnel
Hospitals
Humans
Pandemics*
SARS-CoV-2
Tasmania / epidemiology