Covid-19 may have been the deadliest pandemic the world has experienced in over 100 years. But statistically, these extreme events are not as rare as you think.
According to EurekAlert!, a team of scientists found that the probability of a pandemic with a Covid-19-like impact occurring is about 2% in any given year, meaning that someone born in 2000 would have about 38% of likely to experience one now.
“The most important conclusion is that large pandemics such as 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 authors of the article published in 23 August, in the scientific journal PNAS.
The survey used new statistical methods to measure the scale and frequency of disease outbreaks for which there has been no immediate medical intervention for the past 400 years.
The analysis, which covered diseases such as the Black Death, smallpox, cholera, typhus and new flu viruses, found considerable variability in the rate of occurrence of pandemics in the past. But scientists also identified patterns that allowed them to describe the probabilities of events of a similar scale happening again.
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 similar magnitude to occur ranged from 0.3% to 1.9% per year during the period studied.
In other words, seen in another way, the numbers mean that it is statistically likely that a pandemic of such a scale will occur in the next 400 years.
In addition, the data also showed that the risk of intense outbreaks is growing rapidly. Based on the increasing rate at which new pathogens, such as SARS-CoV-2, have spread among populations over the past 50 years, the study estimates that the probability of new disease outbreaks is likely to triple in the coming decades.
The team estimated that a pandemic similar in scale to that of Covid-19 is likely within a 59-year period, a result that, they noted, is “much lower than intuitively expected.”
Although not included in the study, the scientists also calculated the probability of a pandemic that would be able to wipe out all human life, realizing that it could be statistically likely in the next 12,000 years.
As an environmental health scientist, Pan can speculate on why these outbreaks are becoming more frequent, noting that population growth, changes in food systems, environmental degradation and more frequent contact between humans and animals that harbor diseases can be significant factors. (ZAP)