A groundbreaking online tool, SpillOver, assesses hundreds of known viruses by their potential to jump to humans and their overall threat level. Hidden among them could be the pathogen behind the next global outbreak.
SARS-CoV-2 marks the latest virus to spill over from animals to humans, but it's neither the first nor the last. Hundreds of thousands of other pathogens could pose similar dangers. Developed by experts including Zoë Grange from the University of California, the open-access SpillOver platform helps scientists and policymakers prioritize threats for deeper investigation and prevention strategies.
"SARS-CoV-2 is just one example of the thousands of viruses with potential to spill over from animals to humans," says Grange, who led the tool's development. "We must identify and prioritize the highest-risk viral threats to avert another devastating pandemic."
Researchers have identified about 250 known zoonotic viruses that have already jumped to humans, with around 500,000 others showing spillover potential. To rank them, the team evaluated over 30 factors, including the number of infected animal species and human-host interaction frequency, narrowing the list to 887 viruses—many recently discovered, others long-known.
The top 12 are established zoonotics: Lassa virus leads, followed by SARS-CoV-2 and Ebola virus. SARS-CoV-2 doesn't top the list due to knowledge gaps; updated data could elevate it.
Among non-zoonotic viruses, the 229E coronavirus—found in African bats and from the same family as SARS-CoV-2—poses the greatest risk. Another key watch is PREDICT CoV-35, a coronavirus in bats from Africa and Southeast Asia.
As a crowdsourced platform, SpillOver allows researchers to update data or add new viruses, ensuring rankings evolve with emerging evidence.
