Strategies to prevent the next pandemic fall into two main categories:
1. Prevent or prepare for natural spillover
2. Prevent or prepare for man-made pathogens
This community has rightly focused on the second category. A pathogen that is naturally evolving has no incentive to be incredibly deadly- its only "goal" is to spread, and lethality is a by product. Humans, on the other hand, actively try to make pathogens more lethal and transmissible than they would otherwise be, sometimes for research intended to prevent illness and death, and occasionally to create bioweapons intended to kill and spread.
In Toby Ord's The Precipice, he estimates the risk of an existential catastrophe from a "naturally" arising pandemic in the next century is over 300 times less likely than that of an existential catastrophe from engineered pandemics. Our efforts should continue to focus on this relatively neglected tail which contributes much more to our civilization's risk of extinction or unrecoverable collapse.
We should also continue to pressure people and organizations to not take actions that decrease the threat of 1 but increase the threat of 2; examples of these kinds of action include virus hunting, especially if the results are then categorized and posted online, and some of the research intentionally making pathogens more transmissible or deadly given our track record of unintentional lab leaks, even from BSL-4 labs.
However, this correct focus on category 2 risks does not preclude reducing category 1 risks as well. We have seen how a mildly deadly pathogen like SARS-CoV-2 can cause tremendous harm and suffering, with Our World in Data reporting almost 7 million confirmed deaths worldwide. The origins of this virus are still debated, but many have argued that the mere plausibility that a virus like this could have come from a lab should be enough to act to prevent any future lab leak of a deadly and transmissible virus. I agree, and I think this logic also goes the other way: the mere plausibility of a pandemic virus capable of killing millions emerging naturally should be enough to motivate us to prevent and prepare for future pathogens of zoonotic origin, given those actions do not increase the risk from pathogens intentionally or unintentionally released by humans.
This paper is focused on how we can reduce the risk of pathogen spillover, taking a category 1 approach. Here are some selected quotes from the article, along with my takeaways:
In many emerging infectious disease hotspots, little intact forest remains, and spillover events occur because dense human and domestic animal populations live closer to wildlife and commercial activities might involve intentional (e.g., wildlife trade) or unintentional contact with wildlife (26). Such areas make up only 4% of global area (10% of tropical area), but account for 60% of global spillover risk.
Actions to reduce local risk for zoonotic diseases can be simple. For example, Nipah virus infection risk can be reduced by covering the shaved areas of palm tree trunks and sap vessels, thus preventing contamination with excrement of bats that feed on these palms (28). Where contact cannot be eliminated, improved practices, such as better sanitary practices during wildlife butchering, can minimize spillover (29).
Controlling vaccine-preventable diseases in domestic animals also should be prioritized. Vaccination benefits communities and domestic animals through reduced illness and death from vaccine-targeted disease. Vaccination also reduces the spread of emerging infectious diseases because diagnosis can be delayed when emerging infectious diseases have similar clinical signs to vaccine-preventable diseases. For example, identification of highly pathogenic avian influenza in chickens frequently is delayed in areas with low Newcastle disease vaccination rates (45,47). Similarly, control for outbreaks of African swine fever (ASF), a disease with no effective vaccine, is hampered by low vaccination rates against classical swine fever (CSF) because the diseases have similar clinical signs, making ASF differentiation difficult in herds not vaccinated against CSF (48). In China, a 2019 pork shortage caused by ASF might have increased consumer demand for wildlife, thereby increasing the risk of pathogen spillover (2).
For pandemic prevention, the primary focus should be live and freshly butchered wild birds and mammals because those pose the highest risk for spillover.
In numerous countries, wildlife consumption, especially in urban centers, is not required for food security; rather, wildlife is consumed as a luxury, as a status symbol, or for perceived health reasons. In China, the price for wildlife is generally 2- to 5-fold higher than for pork, the most common animal protein source in the country, and even higher for exotic, endangered, or illegally obtained species (52,53). Reducing urban demand for wildlife will have a positive effect on IPLCs by reducing economic incentives to those supplying the trade and leaving more wildlife for IPLC subsistence needs. A strategy to ensure recognition and support of IPLC rights is vital, but that support must not be used as a smokescreen to continue business-as-usual in commercial markets and trade.
Many human febrile illnesses in low-income countries never reach the health system and are not thoroughly evaluated; thus, many viral infections are never diagnosed (61,62).
Mounting evidence suggests that zoonotic pathogen spillover occurs more frequently than previously known. A study of exposure to batborne SARS-related coronaviruses suggested that ≈66,000 persons are infected with SARS-related coronaviruses annually in South and Southeast Asia (65).
My takeaways:
- Even vaccinating for diseases that are unlikely to cause a pandemic, in both humans and animals, can help our response to pandemic capable pathogens, by eliminating diseases that cause similar symptoms and by making health and food systems more resilient.
- Increasing sampling of pathogens in wildlife seems like a bad idea, but increasing surveillance of human diseases, especially undiagnosed human diseases, seems like an intervention that would have positive effects for the people being tested, for basic science, and for pandemic preparedness.
- While reducing category 1 risks is important, we can't entirely eliminate the possibility of a natural pandemic. We need to continue investing in preparedness and response measures to mitigate the impact of such events, including global surveillance systems, vaccine development, and rapid deployment of medical supplies and personnel in the event of an outbreak.
