And the chance that one will break out will also become much greater in the coming decades.

The current COVID-19 pandemic is arguably the deadliest viral outbreak the world has seen in more than a century. But statistically, such extreme events aren’t as rare as you might think, researchers warn in a new study.

The study

In the study, researchers estimated the severity of a future pandemic and the annual probability of such an event. To get a good estimate, the research team first used statistical methods to calculate the size and frequency of disease outbreaks that have occurred over the past four centuries. For example, they analyzed the plague, smallpox, cholera, typhoid and new flu viruses. Finally, based on this, they were able to calculate the probability of similar events happening again.

Probability

The team found that the probability of a pandemic of similar magnitude to COVID-19 is about 2 percent in each year. This means that someone born in the year 2000 now has about a 38 percent chance of experiencing a pandemic. In the case of the deadliest pandemic in modern history – the Spanish flu, which killed more than 30 million people between 1918 and 1920 – the probability of a pandemic of comparable magnitude varies between 0.3 and 1.9 percent. per year. In other words, the probability of a similar, extreme pandemic occurring in the next 400 years is statistically possible. “Most importantly, major pandemics such as COVID-19 and the Spanish flu are relatively likely,” said study researcher William Pan.

The researchers also calculated the likelihood that a future pandemic will wipe out the entire human species. How big is that chance? The findings show that this could be statistically likely within 12,000 years.

Not only are major pandemics much less rare than you might think, the chance that one will break out will also be many times greater in the coming decades. Based on the increasing rate at which new pathogens such as SARS-CoV-2 spread among humans over the past 50 years, the researchers estimate that the likelihood of new disease outbreaks may even triple in the coming decades. What’s more, a pandemic that can measure up to COVID-19 in scale could happen within 59 years. And who is shocked by this; the researchers write that this is ‘much lower than they intuitively expected’.

Why is the risk of outbreaks increasing in the future? That can have several causes. The researchers argue that population growth, changes in food systems, environmental degradation and increasingly frequent contact between humans and disease-carrying animals could all be important factors.

That does not mean, however, that we can sit back for the next 59 years or that we will not have to worry about a similar extreme pandemic as the Spanish flu for the next 300 years. They are calculations based on averages. “Such events are equally likely in any year,” warns Gabriel Katul. “If there is a flood today that occurs every 100 years, then one can mistakenly assume that we will be safe for the next 100 years. That impression is really wrong. The following year we could have to deal with such a flood again.”

lesson

According to the researchers, there is an important lesson to be learned here. “Understanding better that pandemics are not so rare should increase our willingness to prevent and manage them in the future,” Pan concludes. According to the researchers, the findings highlight the need to rethink our view of pandemic risk and preparedness. “It highlights the importance of an early response to disease outbreaks,” Pan said. “We also need to better monitor pandemic risk, both on a local and global scale.”

The researchers hope the current research will encourage other scientists to look for the factors that make devastating pandemics more likely and how they can be prevented.