News
19 April, 2025
Silent spreaders lasting impacts
A new QUT behavioural economics study has revealed that undetected COVID-19 infections — particularly among asymptomatic individuals who avoided testing and isolation — significantly prolonged the pandemic’s spread and distorted public health responses.
The research, led by Associate Professor Jayanta Sarkar (pictured), found that personal testing and isolation behaviour played a key role in shaping disease transmission.
Early reliance on symptom-based testing missed many asymptomatic cases, especially when perceived risk was low.
However, testing increased during reported case surges, as higher risk perception encouraged more people to test and self-isolate.
“This created a feedback loop,” Prof Sarkar said.
“Rising cases prompted more testing, which curbed transmission. But as cases declined, so did testing, leading to ongoing, undetected spread.”
The study, published in PLoS One, showed that the proportion of asymptomatic infections may have ranged from 1.2 to 91.9 per cent globally.
Prof Sarkar said the research highlighted the mental trade-offs people made around testing, such as income loss or social isolation.
Without symptoms, many relied on news and community data to gauge infection risk.
The study calls for accessible, affordable rapid testing and global surveillance infrastructure to detect future outbreaks early.
“Failing to identify asymptomatic carriers means underestimating the real scale of disease and its severity,” Prof Sarkar said. “Incentivised testing and strong data-sharing systems are essential to save lives and better manage future pandemics.”
The findings underscore the role of individual behaviour in pandemic control, supporting calls for stronger public health messaging and improved testing strategies for the next global health crisis.
