Scientists predict when the next pandemic as bad as COVID-19 might happen

Another pandemic just as bad as COVID-19 is likely to happen within the lifetime of most people reading this article, US scientists say. 

Since its discovery in China in late 2019, the SARS-CoV-2 virus has killed millions and infected hundreds of millions, and changed life as we know it. Excluding AIDS - which the World Health Organization classifies as a 'global epidemic' - COVID-19 is the worst pandemic since the Spanish Flu a century ago. 

Researchers at Duke University analysed the frequency of past outbreaks of disease like smallpox, cholera, typhus and influenza, and how widespread they were. Based on this, they calculated each year there was about a 2 percent chance of a pandemic as bad as COVID-19 happening - so about twice a century, on average.

But the growing threat of viruses making the leap from animals to humans thanks to our encroachment on the natural environment means it's becoming more and more likely.

A report from United Nations' Intergovernmental Platform on Biodiversity and Ecosystem Services last year concluded there were nearly a million viruses out there that could make the jump to humans, and there was "no great mystery" what would be the cause - human encroachment on wildlife habitats. 

"Diseases that we get like COVID come from wildlife - and so the more that we encroach and go into habitats where wildlife are, the more complex they are and the more likely that these emergent events will happen," David Hayman of Massey University's School of Veterinary Science told Newshub.

The new research suggests another "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", a pandemic with mortality counted in the millions is "likely within a span of 59 years". It could even start before this one's over.

"When a 100-year flood occurs today, one may erroneously presume that one can afford to wait another 100 years before experiencing another such event," says Gabriel Katul, one of the paper's authors. "This impression is false. One can get another 100-year flood the next year."

The good news is that pandemics as bad as the Spanish Flu, which killed up to 5 percent of the world's entire population, are only expected to happen on average every 400 years or so. 

The bad news is the maths also suggests a pandemic bad enough to wipe out humanity is "statistically likely" within the next 12,000 years.

The worst to date have been the Antoine Plague, the Black Death of the 1300s through to the 1600s, HIV/AIDS, Spanish Flu and the Plague of Justinian. Of those, three were caused by a single bacterium - Yersinia pestis - which is still around. 

The last pandemics comparable to COVID-19 were the 1957-58 Asian flu pandemic and the Hong Kong flu pandemic of 1968-69, which killed up to 4 million people each. 

While the mortality rate of COVID-19 - a coronavirus - remains a matter of debate, it's likely to be more lethal than both of those flu viruses, each of which were slightly more deadly than typical flu, not to mention the unknown long-term effects of conditions such as long COVID. 

The latest study was published in journal PNAS.