Practicing viral vigilance will help scientists detect and contain future outbreaks
Imagine how different the COVID-19 pandemic might have been if scientists had been armed with more information about the virus before the first major human outbreaks occurred…
Although humankind has faced many viruses and other pathogens for millennia, modern outbreaks have increasing potential to spread internationally and wreak havoc on every aspect of society – the stark reality presented by COVID-19. In early 2022, the IMF estimated that the cost of the pandemic will exceed US$12.5 trillion by 2024 (1) – and that’s not to mention the unquantifiable cost of lives lost, long-lasting health effects, and disruption in education, socialization, technological advancement, and more.
The acceptance of mRNA technology has opened the door to other rapid-fire vaccine development platforms, which enables preemptive vaccine design and rapid deployment for future epidemics. One modeling study estimated that almost 600,000 COVID-19 deaths could have been prevented if vaccination efforts had reached the World Health Organization’s 40 percent coverage target by the end of 2021 (2) – a feat made easier if more vaccines had been available sooner.
Looking ahead, a key component of pandemic preparedness will involve proactive monitoring of viruses as they evolve and circulate between different populations and species. “Virus hunting” will require significant funding and effort from a broad coalition, but it is a worthwhile cost to prevent or mitigate the next pandemic.
How do outbreaks occur?
Viruses that originated in animals and jumped the species barrier – aka “zoonotic spillover” – accounts for 60–75 percent of infectious diseases that plague humans (3), including HIV, Dengue fever, and SARS. Any interaction between humans and wild animals can increase the risk for zoonotic spillover, including hunting, exotic pet trades, and habitat encroachment that results from deforestation and urban expansion. And it’s not just new viruses we have to worry about – outbreaks can also come from familiar pathogens already circulating in human populations; for example, polio, ebola, Zika virus, and mpox.
The risk of new outbreaks is also high in areas of inequitable vaccination access or low uptake, which creates higher concentrations of unvaccinated individuals who can rapidly spread the disease to those around them.
Tracking down viruses
Virus hunting requires strategic, multi-pronged approaches. It is unrealistic to sample every animal and human population; however, the risk of new outbreaks isn’t evenly distributed. Some virus hotspots are far more likely to produce new, mutated viruses and create opportunities for spillover – making them targets for closer monitoring. Generally, these hotspots include areas where a large number of species co-habitat, such as jungles and rainforests.
Virology expert Ed Rybicki from the University of Cape Town (located at the heart of the South African viral hotspot) says an ideal testing plan for novel viruses would include scans of wildlife and domestic animals within a given area, using samples collected from feces, forest and farm runoff, and sewage. This type of environmental surveillance is much more efficient and comprehensive than testing individual animal specimens or humans. Once scientists have a virus’ genetic sequence from agnostic environmental sampling and laboratory testing of known diseases, they can use simpler, cheaper tools for ongoing monitoring. Rybicki points out that hotspots are often widely distributed in remote locations, so monitoring cities is a good “tripwire” to detect viruses that begin spreading from rural points of origin. He suggests that small devices could be installed on public transport and in community settings such as hospitals and schools to monitor the viral “airome” via miniaturized sensors or chips with genetic sequences that are shared between known viruses.
However, although airome sampling presents an intriguing concept for respiratory pathogens, wastewater surveillance is the most robust and established epidemiological tool for broad community monitoring. Scientists have been using the technique for decades to track diseases, such as polio, but the method has advanced in recent years with extra-sensitive technologies, such as Droplet Digital PCR, which not only detects specific viruses but accurately quantifies how prevalent they are at a given time point. This has proved its utility and gained recognition throughout the COVID-19 pandemic, allowing scientists to track new variants as they emerged and providing early warning of surges to enable proactive public health measures and hospital preparation.
Worth the up-front investment?
The next pandemic is a matter of when, not if. Therefore, pandemic preparedness is a sure investment rather than unnecessary caution. With strategic resource allocation and surveillance integration into existing research programs, it doesn’t have to be costly relative to overall expenditures on other research and healthcare – or compared with the costs of unmanaged outbreaks.
“We could put a sequencing laboratory in each hotspot worldwide to sequence thousands of viruses per day. We could probably automate subunit vaccine development for each of those viruses – whether we needed them or not,” says Barry Holtz, Chief Scientific Officer at Phylloceuticals and a leading expert in the development of fast-track vaccines using plants. “The budget would be mere pixie dust compared with the trillions of dollars the COVID-19 pandemic has already cost the world.”
A Shalal, “IMF sees cost of COVID pandemic rising beyond $12.5 trillion estimate” (2022). Available at: reut.rs/3YZK2sd.
OJ Watson et al., “Global impact of the first year of COVID-19 vaccination: a mathematical modelling study,” Lancet Infect Dis, 22, 1293 (2022). PMID: 35753318.
JH Ellwanger, JAB Chies, “Zoonotic spillover: Understanding basic aspects for better prevention,” Genet Mol Biol, 44, e20200355 (2021). PMID: 34096963.