Pinpointing exactly where the world's next pandemic stems from will be a "futile" exercise until we collect vast amounts of more data, a leading virologist says.
Most viruses that cause disease humans come from other animals - and these so-called "zoonotic" pathogens have triggered epidemics and pandemics in humans for centuries.
The virus behind Covid-19 – SARS-CoV-2 – originally emerged from an animal species, although exactly which species was still being investigated.
In any case, the catastrophe has prompted many people to ask whether we'll be able to catch and stop the next potential pandemic virus.
"What is going to cause the next pandemic is probably the highest-stakes question in studies of infectious disease right now," said ESR and Otago University virologist Dr Jemma Geoghegan, a co-author of a newly-published assessment.
"We sought to determine whether this question could be answered based on our current data."
What's called "zoonotic risk prediction" involved trying to determine which virus families and host groups were most likely to carry potential zoonotic or pandemic viruses.
Geoghegan said virus discovery rates had been rapidly increasing over the past decade.
"This is changing the make-up of virus data in that the more viruses we find, a smaller proportion of them seem to cause disease."
Some scientists have suggested that we might be able to combine available data with sophisticated models to make predictions.
However, the new report, led by Dr Michelle Wille at the University of Sydney and published in the journal PLOS Biology, found that would be a harder feat than we might think.
An obvious problem was predictions to date had been based on tiny datasets.
Despite decades of work, scientists have probably identified less than 0.001 per cent of all viruses, even from the mammalian species from which the next pandemic virus will likely emerge.
Viruses happen to be the most abundant biological entities on Earth - and more than a quadrillion-quadrillion individual ones are thought to exist.
As well, existing data was highly biased towards those viruses that most infected humans, agricultural animals, or which were already known to be zoonotic.
The reality was, the report authors said, that most animals have not been surveyed for viruses, and that viruses evolve so quickly that any such surveys will soon be out of date and so of little value.
"So it's futile to attempt any prediction until we have dramatically increased our understanding of the diversity of viruses in existence," Geoghegan said.
The authors argued that a new approach was needed, involving the extensive sampling of animals and humans at places whey they interact - the "animal-human interface".
"This way, any virus that jumps into humans can be spotted and stopped before it takes hold," Geoghegan said.
Such enhanced surveillance could even help us prevent a global disaster like the Covid-19 pandemic - which has so far killed three million people, and seen more than 140 million infected - ever happening again.
"Viruses are more likely to spill over into human populations in areas where humans interact with wildlife and domestic animals, so this is important for New Zealand too."
In a recently-launched five-year project, Geoghegan was using revolutionary new technology to gain unprecedented insight into viruses within our native and introduced species.
That study, supported with a Rutherford Discovery grant, would also explore what made some viruses leap between species, and others stick with their hosts.
While specific predictions remained tricky, scientists have been able to identify "hot-spots" around the world, where growing human encroachment into natural habitats raised the risk.