Since NSW Health Pathology's breakthrough development of a COVID-19 serology test in February this year, the use of serological testing has become an integral part of our pandemic response.
Serology tests detect antibodies the human body creates to fight SARS-CoV-2, the virus that causes COVID-19, indicating recent or past infection.
The test uses a technique known as immunofluorescence and was developed by Dr Linda Hueston, Principal Hospital Scientist and Chief Serologist at NSW Health Pathology's Westmead laboratory.
Serology is key to knowing the extent of the virus' spread and helps inform our statewide public health response.
Serological testing has many uses, such as determining the extent of infection in a population; estimating the date of exposure and infectious period in confirmed cases; making a retrospective diagnosis in individuals who have recovered from infection prior to testing; and guiding the public health response to an outbreak.
NSW Health Pathology Senior Staff Specialist in Microbiology and Infectious Diseases Dr Matthew O'Sullivan said public health is a lot of detective work and serology or antibody tests can be particularly helpful to explain the missing links in transmission, when someone has had COVID-19 but was not tested at the time.
'It was a great effort for the NSW Health Pathology ICPMR-Westmead lab to rapidly develop and implement routine COVID-19 antibody testing, and now we have several NSW Health Pathology labs offering this service,' Dr O'Sullivan said.
In recent months, the use of serological testing has expanded across the state. In addition to ICPMR-Westmead, COVID-19 serology assays are now available via NSW Health Pathology's laboratories at John Hunter Hospital, Royal North Shore Hospital, Royal Prince Alfred Hospital, Concord Hospital, Randwick campus, Liverpool Hospital, and Westmead ICPMR.
A fact sheet outlining the use of serology in NSW can be found at NSW Health Pathology.
In an evaluation study, 2,753 individuals being swabbed for COVID-19 also had the immunofluorescent antibody test performed.
Of these, 126 were found to be COVID positive via polymerase chain reaction (PCR) swab test, and 115 of these COVID cases had antibodies detected.
Antibodies were detected very rarely in the individuals with negative PCR tests, and where they were present in negative cases they were at very low levels. A paper describing this study is available.
Separately, another serological study, also known as a sero survey or sero surveillance, is underway to help determine the extent of the COVID-19 virus spread among the Sydney population.
The study is a collaboration between the NSW Ministry of Health, NSW Health Pathology, the National Centre for Immunisation and Surveillance (NCIRS), the Kirby Institute at UNSW, Lifeblood and private laboratories.
NSW Health Pathology's team at Westmead has now completed testing around 3,500 residual pathology samples recently collected for the purpose of non-COVID-19 testing, such as cholesterol checks or liver function tests.
The results will provide a better understanding of the extent of the virus in the community and will help guide the evolving public health response to the outbreak, including determining potential changes to current social distancing plans.
Dr Hueston was also recently awarded funding under the NSW Health COVID-19 Research Grants.
Dr Hueston had identified a need to increase the volume of serology testing that can detect the three antibody markers (immunoglobulin G (IgG), immunoglobulin A (IgA), and immunoglobulin M (IgM), as no such commercial test existed. This grant will be used to support her work in developing a suite of new tests that will improve rapid diagnosis of COVID-19.
The data produced through NSW Health Pathology's serology work may also be used to determine immunity against future re-infection or help researchers assess the effectiveness of a COVID-19 vaccine when one becomes available.
