A new study from the University of Edinburgh has introduced a risk-ranking system for RNA viruses that infect humans, designed to help public health officials act faster when the next pandemic threat emerges. The team analyzed decades of virus discovery data and outbreak patterns to create a prioritized list of pathogens based on their potential to cause widespread harm.
Why RNA viruses demand attention
Most viruses with genomes made of RNA evolve rapidly compared to DNA viruses, making them more likely to adapt to new hosts—including humans. While over two million RNA virus species may exist in nature, only 239 have been confirmed to infect people. The Edinburgh team’s catalog narrows this down further by evaluating which of these viruses pose the highest risk of sparking global outbreaks.
The risk of a virus becoming pandemic depends on two core factors: its ability to spread between people and the severity of the disease it causes. Some viruses, like rabies, infect humans but cannot transmit between people, while others, like measles, spread efficiently through the air. The team’s analysis highlights that viruses already capable of human-to-human transmission represent the greatest concern, as they may evolve into more transmissible forms over time.
- Zoonotic viruses (those primarily transmitted from animals) account for two-thirds of the cataloged pathogens. Rabies, for example, remains a deadly threat but has never jumped from person to person.
- Viruses with documented human transmission make up the remaining third. These include well-known pathogens like measles and mumps, as well as emerging threats like bird flu.
The role of transmissibility in outbreak potential
Transmissibility is measured by the basic reproduction number, or R0, which indicates how many people, on average, an infected individual will pass the virus to. A virus with an R0 above 1 can sustain chains of infection, while those below 1 typically die out naturally. However, even viruses with low R0 can pose risks if they evolve or encounter new populations.
The team’s findings align with historical patterns. Zaire ebolavirus, for instance, had caused only sporadic outbreaks until it reached densely populated areas in West Africa in 2014, where its R0 briefly surged. Similarly, the measles virus, with an R0 as high as 18, spreads so efficiently that it has resurged whenever vaccination rates dip. The catalog includes several such pathogens, including Chikungunya, Zika, and mpox, all of which have triggered significant epidemics in recent decades.
Predicting the next Disease X
The researchers used their dataset to model what the next pandemic virus—often referred to as Disease X—might look like. Their work suggests that the ideal candidate would be a highly transmissible RNA virus closely related to existing human pathogens but capable of jumping from animals to people. This profile matches the emergence of SARS-CoV-2, which evolved from a bat coronavirus and spread globally in 2020.
By contrast, viruses like Andes hantavirus or Bundibugyo ebolavirus, which have caused localized outbreaks, lack the transmissibility needed to ignite a global crisis. However, the team warns that even low-risk viruses can become dangerous if they acquire mutations or reach new environments, such as urban centers where vectors like mosquitoes thrive.
The catalog is now publicly available and is expected to guide research funding, surveillance efforts, and preparedness strategies. As climate change and human expansion into wildlife habitats increase the chances of viral spillovers, tools like this will be critical in staying one step ahead of the next outbreak.
AI summary
Bilim insanları, insan sağlığını tehdit eden RNA virüslerini derledi. Hangi virüsler pandemi riski taşıyor? Hangi özellikler bir salgını tetikleyebilir? Detaylı analiz burada.
