Blood samples from around Australia are set to reveal the true number of Omicron cases that have infected residents across the country.
The UNSW’s Kirby Institute and the National Centre for Immunisation Research and Surveillance (NCIRS) have taken 5,000 donor blood samples from across Australia, all of which are from just six weeks after the Omicron peak.
The results could show that cases were 5 to 10 times higher than reported in the initial wave. Due to asymptomatic cases, rapid antigen tests and those who did not get tested, numbers were likely to be much higher.
“We know that relying on reporting of positive tests underestimates the true number of Covid-19 cases, particularly since high vaccine coverage has reduced the proportion of cases with symptoms,” Dr Dorothy Machalek, lead investigator on the project from the Kirby Institute, said in a statement.
“Serosurveys help us understand by how much.”
The research will test for different types of antibodies, looking for part of the virus called the nucleocapsid, which is only present in those with natural immunity, and spike antibodies produced by both infection and vaccination.
“Samples for this survey were taken six weeks after the Omicron peak, which is sufficient for antibodies to have developed in people who were infected during that time,” said NCIRS director Professor Kristine Macartney.
“This, and regular future surveys including another planned in children, will mean we will be able to track the impact of changes in the Covid-19 response to better inform health policy.”