What is serosurveillance?

Serosurveillance provides estimates of antibody levels against infectious diseases and is considered the gold standard for measuring population immunity due to past infection or vaccination. It is an important component of disease surveillance and complements notification, hospitalisation, mortality and immunisation coverage data. National serosurveillance programs are well established in many countries worldwide.

Serosurveillance for SARS-CoV-2 infection

NCIRS is co-leading the Australian COVID-19 Serosurveillance Network and a suite of serosurveys with the Kirby Institute to measure the prevalence of SARS-CoV-2-specific antibodies in target populations. 

SARS-CoV-2 serosurveys provide critical information to estimate the spread of the virus in the Australian community. Our understanding of the epidemiology of COVID-19 in Australia has been predominantly based on the identification of cases who have presented for testing because they are unwell (have symptoms). While this allows us to see the ‘“tip of the iceberg’”, seroprevalence studies provide a broader view of previous SARS-CoV-2 infections, including mild and asymptomatic cases and those who may not have been tested for the virus during their infection. The work involves testing blood (serum or plasma) samples from thousands of Australians for SARS-CoV-2 antibodies. 

Four SARS-CoV-2 serosurveys are currently being led by NCIRS and the Kirby Institute and involving many collaborators. Two of these were conducted following the first wave: one in metropolitan Sydney and another nationally. Another two serosurveys have taken place following the second epidemic wave, one in metropolitan Melbourne and another among children nationally. Funding for this work has been provided by the Australian Partnership for Preparedness Research on Infectious Disease Emergencies (APPRISE) Centre of Research Excellence, Snow Medical Foundation, Australian Government Department of Health and the Victorian Department of Health and Human Services. 

Read the results of the serosurvey here

Read full study on MJA website

Visit NCIRS COVID-19 response page to read more about serosurveys currently underway.

Vaccine preventable disease serosurveillance 

NCIRS, in collaboration with the Centre for Infectious Diseases and Microbiology Laboratory Services (CIDMLS), at Pathology West – ICPMR, Westmead, commenced a national serosurveillance program in 1996, and has been conducting national serosurveys at approximately 5-yearly intervals. Each serosurvey involves collecting a bank of 7,000–13,000 plasma or serum specimens from diagnostic laboratories throughout Australia that receive samples from hospitalised and ambulant people. The specimens are collected opportunistically from residual/leftover specimens submitted for testing that would otherwise have been discarded and are randomly selected to represent the Australian population.

The collection and storage of specimens is managed by CIDMLS, as is the testing for immunity to the VPDs of interest using disease-specific in-house or commercial serological assays. NCIRS is responsible for the direction of the national program and the subsequent data analysis and interpretation of the serological results. Ethical approval is obtained for each serosurvey. 

Serosurvey 1 (1996–1999): measured population immunity to measles, mumps, rubella, varicella, hepatitis A, hepatitis B, hepatitis C, diphtheria, tetanus, polio and pertussis.

Serosurvey 2 (2002): measured population immunity to measles, rubella, varicella, hepatitis B, pertussis, meningococcal C, cytomegalovirus and Helicobacter pylori.

Serosurvey 3 (2007): measured population immunity to measles, mumps, rubella, varicella, pertussis, meningococcal C, diphtheria, tetanus and hepatitis B.

Serosurvey 4 (2012–2013): measured population immunity to measles, mumps, rubella, human papillomavirus and polio.

Serosurvey 5 (2018–2019): collection of specimens is currently underway.

A full list of publications from our serosurveillance program is available here.

Potential applications of our serosurveillance program
  • Examining trends of immunity over time 
  • Evaluating the impact of vaccination programs
  • Identifying groups at risk
  • Informing immunisation policy
  • Disease modelling
  • Estimating the burden of specific VPDs
  • Predicting potential outbreaks
  • Contributing to verifying disease elimination
  • Identifying infection with new or emerging pathogens and assisting with public health responses
Acknowledgements

We wish to thank the staff of all the laboratories that have contributed sera/plasma to our national serosurvey program for their valuable contribution.

Last updated June 2021