How likely are we to encounter a new pandemic in our lifetime

Experiencing a pandemic like Covid-19 would seem more common than we can imagine. Data from an international study warns us about the future

Photo: Martin Sanchez / Unsplash The Covid-19 pandemic seemed to us an exceptional event, capable of disrupting our lives, but absolutely rare. Yet human beings have always had to deal with the great epidemics, from the black plague of the fourteenth century to the HIV pandemic, passing through the Spanish flu of 1918.

Now, statistics also seem to confirm this: a study conducted by several universities, including the Department of Civil and Environmental Engineering of the University of Padua, revealed that major pandemics are much more common than one might expect. In fact, each of us has a 38% chance of experiencing a Covid-19-like impact pandemic at least once in our lifetime, and this trend looks set to increase. The results of the research have been published in the scientific journal Pnas.

Investigating the history of epidemics

Although epidemics are well known in human history, estimates on the probability of their occurrence they are either completely missing, or they offer scientists belated projections. This is a problem: although forecasts on the outbreak of new infectious diseases may arouse anxiety, it is important to know how likely it is that a pandemic like Covid-19 will hit us again, so that we can be better prepared.

This is why a group of researchers from the University of Padua, Duke University in the United Kingdom and Marquette University in the United States have estimated the likelihood with which a new pandemic could arise.

To do so, it drew from the history of infectious diseases: researchers, in fact, collected and analyzed a global data set of major epidemics spanning four centuries, from the year 1600 to today. They found 476 documented outbreaks, about half of which had a known death toll - for example, 145 caused fewer than 10,000 deaths. The analysis did not include ongoing epidemics, such as Covid-19, malaria or the HIV epidemic.

"Relatively probable" and destined to increase

"The more important is that major pandemics like Covid-19 and the Spanish flu are relatively likely, ”said William Pan, a researcher at Duke University, one of the authors of the study. From the analysis of the data, in fact, it emerged that, although the estimated annual number of epidemics is enormously variable (an epidemic such as the Spanish flu of 1918-1920, in the last 4 centuries could have occurred every year with a probability between 0.3% and 1.9%), the possibility of an extreme epidemic occurring slowly decreases with the intensity of the epidemic.

This means that we have a rather high probability of observing pandemics similar to Covid-19: the researchers estimate is 2% every year, which, added up over the course of a person's life, amounts to about 38%. And it seems that this is destined to increase.

The research team, in fact, warns about the future: the high probability of observing pandemics similar to Covid-19 could increase in the coming decades, up to double, due to the increase in the onset rates of new infectious diseases due to environmental changes. A pandemic like the one we are experiencing, therefore, is anything but out of the ordinary, and perhaps, in the course of our life, we will have to come to terms with something similar.

After all, even earlier of Sars-Cov-2, the incidence rate of new zoonoses, such as Ebola, bird flu or swine flu was steadily increasing. Knowing what lies ahead, however, could be a great starting point for tackling new pandemics. "This underscores the importance of a timely response to outbreaks and developing surveillance capabilities on a local and global scale, as well as setting a research agenda to understand why major outbreaks are becoming more common," Pan says.


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