Most of us hope the coronavirus pandemic will be a once-in-a-lifetime event, but it may be "relatively likely" that another global infectious outbreak will occur in the near future.
Scientists from the University of Padua in Italy analysed the scale and frequency of outbreaks that had "no immediate medical intervention" over the past 400 years – including the plague, smallpox and cholera.
Results – published in the journal Proceedings of the National Academy of Sciences – suggest there is a 2% chance a pandemic on the scale of COVID-19, the disease caused by the coronavirus, could occur in any given year.
While many of us are keen to return to life as once knew it – with unhindered travelling, the option to work in an office and no fear of cancelled plans – a similar global outbreak is "likely" to occur in the next 59 years, the scientists found.
An infection that wipes out humans is even expected in the next 12,000 years.
"When a 100-year flood occurs today, one may erroneously presume one can afford to wait another 100 years before experiencing another such event," said study author Dr Gabriel Katul.
"This impression is false. One can get another 100-year flood the next year."
The scientists used a new statistical model to measure past outbreaks and the probability of similar events occurring in the future.
When it comes to the coronavirus specifically, someone born in 2000 would have had a 38% chance of experiencing a similarly sized pandemic by now.
The prevalence of newfound infectious outbreaks, like the coronavirus, is set to triple over the next few decades, becoming much more common "than intuitively expected".
This has been partly put down to population growth, environmental degradation and increased contact between humans and disease-carrying animals.
Spanish flu was the deadliest pandemic in modern history, killing more than 30 million people between 1918 and 1920. Over the Padua study period, the probability of a similar outbreak occurring came in at 0.3% to 1.9%.
It is therefore statistically likely a pandemic of such a severe scale will occur within the next 400 years, according to the scientists.
"The most important takeaway is large pandemics like COVID-19 and the Spanish flu are relatively likely," said co-author Dr William Pan.
Efforts should therefore be made to prevent and control future outbreaks.
"This points to the importance of early response to disease outbreaks and building capacity for pandemic surveillance at the local and global scales, as well as for setting a research agenda for understanding why large outbreaks are becoming more common," said Dr Pan.
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