Calculations have shown that the annual risk of dangerous epidemics can increase up to three times in the coming decades. And an outbreak of a disease that can kill all people on the planet is likely within the next 12 thousand years.
The persistent Covid-19 pandemic, which has claimed the lives of nearly four and a half million people, will be the deadliest outbreak in a century (aside from HIV / AIDS, which has killed at least 36 million since the 1980s). However, statistically, such extreme events are not as rare as they seem: before the coronavirus, there was swine flu in 2009, and in the past century, outbreaks have occurred on average every 20 years.
Scientists at the University of Padua in Venice have compiled a global survey of data on epidemics from 1600 (plague, smallpox, cholera, typhoid and influenza viruses) to today and analyzed them using modern statistical methods to estimate the likelihood of new outbreaks. They not only identified differences in the rate of development of pandemics, but also identified some patterns. Diseases were taken into account, due to which at least 10 thousand people died. HIV / AIDS and malaria were excluded from the sample.
The deadliest world epidemic in history is the Spanish flu, or "Spanish flu", which lasted from 1918 to 1920 and killed between 17 million and 100 million people. According to scientists, the risk of developing a similar outbreak is growing from 0.27 to 1.9 percent annually. Consequently, the calculations suggest that a similar pandemic could occur every 332-489 years. As for Covid-19, in this case, the probability of recurrence increases by about two percent a year: which means that for a person born in 2000, it is estimated at more than 38 percent by now and will happen around 2078.
At the same time, the data showed that the chances of intense outbreaks are rapidly increasing as pathogens like SARS-CoV-2 are spreading rapidly. As the researchers note, the risk of outbreaks of new diseases could triple in the next few decades. Based on this, a pandemic similar in scale to the Spanish flu will repeat itself every 127 years, and the one that would destroy all life on Earth will happen within 12 thousand years.
However, scientists warn: from their results it does not follow that humanity receives a delay from dangerous diseases until at least the 2080s or even 300 years. Such events have an equal likelihood of developing in any year during the specified period. “When the largest flood in 100 years occurs, it can be mistakenly assumed that the next one will only take place in another 100 years. But next year another such flood may occur,”the authors of the work noted.
While the purpose of statistical analysis is to identify risks, rather than explain what affects them, scientists hope the findings will lead to a deeper study of the factors that increase the risk of deadly pandemics.