Study reveals likelihood of further pandemics is increasing
Extreme events such as the Covid-19 pandemic aren’t as rare as we may think, according to new analysis of novel disease outbreaks over the past 400 years
The study, published in the Proceedings of the National Academy of Sciences, used a newly assembled record of past outbreaks to estimate the intensity of those events and the annual probability of them recurring.
It found the probability of a pandemic with similar impact to Covid-19 is about 2 per cent in any year, broadly meaning that someone born in the year 2000 would have about a 38 per cent chance of experiencing one by now. This probability is also growing, which the authors say highlights the need to adjust perceptions of pandemic risks and expectations for preparedness.
“The most important takeaway is that large pandemics like Covid-19 and the Spanish flu are relatively likely,” said William Pan, Associate Professor of Global Environmental Health at Duke University and one of the paper’s co-authors. Understanding that pandemics aren’t so rare should raise the priority of efforts to prevent and control them in the future, he added.
Likelihood of another outbreak is increasing
The data show the risk of intense outbreaks is growing rapidly. Based on the increasing rate at which novel pathogens such as SARS-CoV-2 have broken loose in human populations in the past 50 years, the study estimates that the probability of novel disease outbreaks will likely grow three-fold in the next few decades.
Using this increased risk factor, the researchers estimate that a pandemic similar in scale to Covid-19 is likely within a span of 59 years, a result they write is ‘much lower than intuitively expected’.
As an environmental health scientist, Pan can speculate on the reasons outbreaks are becoming more frequent, noting that population growth, changes in food systems, environmental degradation and more frequent contact between humans and disease-harbouring animals all may be significant factors. He emphasised the statistical analysis sought only to characterise the risks, not to explain what is driving them.
But at the same time, he hopes the study will spark deeper exploration of the factors that may be making devastating pandemics more likely – and how to counteract them.
Meanwhile, international organisations have come together to improve the understanding of how diseases with the potential to trigger pandemics emerge and spread.