THE number of Australians with covid might be five times higher than reported, according to a new report.

Infection rates between March and August were on average 6.2 times higher than reported cases across 15 countries surveyed in a new report by researchers from Ikigai Research, The ANU and the University of Melbourne, published in “Royal Society Open Science”.

Australia had the best level of detection among the 15 countries at the end of April, but the rate of infection may still have been five times higher than what was officially reported at the end of August, according to the report.  

This means as many as 130,000 Australians are possibly infected with covid, or have recovered from the virus, with the true rate of infection being 0.48 per cent not the reported 0.10 per cent.

ANU co-author Professor Quentin Grafton said the study estimates that the true number of infections across a combined population of more than 800 million people in 11 European countries, as well as Australia, Canada, South Korea and the US.

“We found COVID-19 infections are much higher than confirmed cases across many countries, and this has important implications for both control and the probability of infection,” says Prof Grafton.

“Our analysis has found more than 5.4 million in the UK – 8 per cent of the population – are or have been infected with the coronavirus.

“These findings raise serious questions about how we deal with all facets of the coronavirus pandemic, including ongoing morbidity and life-long health impacts for people who have been infected, how we implement and manage lockdowns, and how we make sure we are on top of this pandemic more broadly.”

The new research used “backcasting”, a process that examines covid related fatalities and compares it with the time from infection to symptoms and time from symptoms to death. 

“Simply put, we analysed statistics on how many people had died from COVID-19 in a given country and then worked backwards to see how many people would have to have been infected to arrive at that number of deaths,” says Dr Steven Phipps, from Ikigai Research.

“Our method is a novel and easy-to-use method for estimating the true infection rate wherever there is reliable data on the number of fatalities attributable to COVID-19.”  

There are advantages to this method says Prof Grafton.

“Our approach is particularly advantageous in locations where there is little testing or limited capacity to forecast rates of infection but where there is a need, for the purposes of public health planning, for a population measure of COVID-19 infection,” he says.