A STUDY published today in the Medical Journal of Australia shows that there was “very limited community transmission” of COVID-19 in Sydney during the first wave of the pandemic.
Associate Professor Heather Gidding, from the School of Public Health and Community Medicine at UNSW Sydney, and colleagues analysed data from de-identified residual blood specimens from public and private laboratories and Australian Red Cross Lifeblood collected between April and June 2020, sampled by geographic location across 10-year age groups.
Their aim was to estimate SARS-CoV-2-specific antibody seroprevalence among three subpopulations in Sydney (20-39-year-old women undergoing antenatal screening, 20-69-year-old plasmapheresis blood donors, and people of all ages having blood tests at selected diagnostic pathology services—general pathology) following the first epidemic wave of COVID-19 in Australia.
Of 5339 specimens, 38 were positive; there were no apparent patterns by age group, sex, or geographic area. Adjusted seroprevalence estimates were 0.15% for people of all ages having a general pathology blood test, 0.79% for women aged 20-39 years undergoing antenatal screening and 0.29% for blood donors aged 20-69 years. When restricted to 20-39 year olds, the age group common to all three collections, estimates were 0.24% for general pathology, 0.79% for antenatal screening and 0.69% for blood donors.
“Seroprevalence well under 1% in all three subpopulations indicates limited community transmission during the first COVID-19 epidemic wave in Sydney,” Gidding and colleagues concluded.
“These findings indicate early and successful control of COVID-19, but also highlight the need to maintain efforts to mitigate further transmission.
“Our serosurveillance approach provides a feasible framework for repeated examination of SARS-CoV-2 transmission over time. Similar methods are being used in a national serosurvey and may also be important in evaluating population-level immune responses following the introduction of COVID-19 vaccines.”
Published via the Journal’s pre-print process, the study has not yet been peer reviewed. It is available at https://www.mja.com.au/journal/2020/seroprevalence-sars-cov-2-specific-antibodies-sydney-australia-following-first and is open access.
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- Cate Swannell