Another pandemic on the scale of Covid-19 is likely to strike the world within the next 60 years, researchers have warned, and they could become much more common.
Covid-19 is one of the deadliest viral outbreaks in more than a century, according to a team led by experts from the University of Padua in Italy, who studied the spread of diseases around the world over the past 400 years to predict future risk.
They found that statistically, extreme pandemics aren’t as rare as previously assumed, becoming more likely, and the next one will happen by 2080.
The US researchers found that the likelihood of a pandemic with similar impact to Covid-19, and on a similar global scale, is about two per cent in any year.
This means that someone born in the year 2000 would have about a 38 per cent chance of experiencing one, and will experience another by their 60th birthday.
They didn’t explore the reason behind the increasing risk, but say it is likely due to population growth, changes in food systems, environment degradation and more frequent contact between humans and disease-harbouring animals.
The team also found that the probability of another major pandemic is ‘only growing,’ and that we should be better prepared for future risks.
Another pandemic on the scale of Covid-19 is likely to strike the world within the next 60 years, researchers have warned, and they could become much more common
ZOONOTIC DISEASES: THESE ARE VIRUSES USUALLY STARTED IN WILD ANIMALS THAT CAN PASS TO OTHER SPECIES AND SURVIVE
Zoonotic diseases are able to pass from one species to another.
The infecting agent – called a pathogen – in these diseases is able to cross the species border and still survive.
They range in potency, and are often less dangerous in one species than they are in another.
In order to be successful they rely on long contact with different animals.
Common examples are the strains of flu that have adapted to survive in humans such as H5N1, H7N9 and H5N6 that started in birds.
Influenza is zoonotic because, as a virus, it can rapidly evolve and change its shape and structure.
There are examples of other zoonotic diseases, such as chlamydia.
Chlamydia is a bacteria that has many different strains in the general family.
Study author Marco Marani and team used new statistical methods to measure the scale and frequency of disease outbreaks with no immediate medical intervention.
Their analysis covered plague, smallpox, cholera, typhus and a range of new influenza viruses over the past four centuries.
They found considerable variability in the rate at which pandemics have occurred in the past, but also found patterns in the outbreak frequency.
This allowed them to predict the chance of similar-scale events happening again.
‘The most important takeaway is that large pandemics like COVID-19 and the Spanish flu are relatively likely,’ said co-author William Pan, from Duke University.
‘Understanding that pandemics aren’t so rare should raise the priority of efforts to prevent and control them in the future.’
In the case of the deadliest pandemic in modern history, Spanish Flu, which killed over 30 million people from 1918 to 1920, the risk of a similar event happening again ranged from 0.3 per cent to 1.9 per cent per year.
Taken another way, those figures mean it is statistically likely that a pandemic of such extreme scale would occur within the next 400 years.
The team also found that the risk of intense outbreaks, that is those on a scale similar to Covid-19 or the Spanish Flu, is growing rapidly.
They looked at the increasing rate at which new pathogens such as SARS-CoV-2 have broken loose in human populations in the past 50 years as part of the new research.
This revealed that the probability of new disease outbreaks will likely grow three-fold in the next few decades.
Using this increased risk factor, Marani and colleagues estimate that a pandemic similar in scale to Covid-19 is likely within a span of 59 years, a result they write is ‘much lower than intuitively expected.’
They also calculated the probability of a pandemic capable of eliminating all human life, finding it statistically likely within the next 12,000 years.
‘That is not to say we can count on a 59-year reprieve from a Covid-like pandemic, nor that we’re off the hook for a calamity on the scale of the Spanish flu for another 300 years,’ according to paper co-author Gabriel Katul from Duke.
‘Such events are equally probable in any year during the span,’ he explained, adding that 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.
‘This impression is false. One can get another 100-year flood the next year.’
Covid-19 is one of the deadliest viral outbreaks in more than a century, according to a team led by experts from the University of Padua in Italy, who studied the spread of diseases around the world over the past 400 years to predict future risk
Pan says outbreaks are becoming more frequent in part due to population growth, changes in food systems, environment degradation and more frequent contact between humans and disease-harbouring animals.
He said the statistical analysis sought only to characterise the risks, not to explain what is driving them, but hopes it will spark deeper exploration of those reasons.
‘This points to the importance of early response to disease outbreaks and building capacity for pandemic surveillance at the local and global scales,’ said Pan.
‘As well as for setting a research agenda for understanding why large outbreaks are becoming more common,’ he added.
The findings have been published in the journal Proceedings of the National Academy of Sciences.
THE CAUSE BEHIND EUROPE’S BUBONIC PLAGUES
The plague, caused by the bacterium Yersinia pestis, was the cause of some of the world’s deadliest pandemics, including the Justinian Plague, the Black Death, and the major epidemics that swept through China in the late 1800s.
The disease continues to affect populations around the world today.
The Black Death of 1348 famously killed half of the people in London within 18 months, with bodies piled five-deep in mass graves.
When the Great Plague of 1665 hit, a fifth of people in London died, with victims shut in their homes and a red cross painted on the door with the words ‘Lord have mercy upon us’.
The pandemic spread from Europe through the 14th and 19th centuries – thought to come from fleas which fed on infected rats before biting humans and passing the bacteria to them.
But modern experts challenge the dominant view that rats caused the incurable disease.
Experts point out that rats were not that common in northern Europe, which was hit equally hard by plague as the rest of Europe, and that the plague spread faster than humans might have been exposed to their fleas.
Most people would have had their own fleas and lice, when the plague arrived in Europe in 1346, because they bathed much less often.