Study provides a blueprint for controlling emerging infectious diseases and future pandemics by preventing “spillover” of diseases from animals into humans.
Researchers from Harvard T.H. Chan School of Public Health have provided three cost-effective actions to help decision-makers prevent future pandemics by stopping the “overflow” of infectious diseases from animals into humans.
Prevention techniques include better surveillance of pathogens, better management of wildlife trade and hunting, and reduced deforestation. The annual costs of these ‘primary pandemic prevention’ actions ($20 billion) are less than 5% of the lowest estimated value of lives lost from emerging infectious diseases every year, less than 10% of the economic costs, and provide substantial co-benefits.
“If COVID-19 taught us anything, it is that testing, treatments, and vaccines can prevent deaths, but they do not stop the spread of viruses across the globe and may never prevent the emergence of new pathogens. As we look to the future, we absolutely cannot rely on post-spillover strategies alone to protect us,” said Dr Bernstein of Harvard Chan C-CHANGE. “Spending only five cents on the dollar can help prevent the next tsunami of lives lost to pandemics by taking cost-effective actions that stop the wave from ever emerging, instead of paying trillions to pick up the pieces.”
The research by 20 experts, published in Science Advances, was led by Dr Aaron Bernstein, director of the Center for Climate, Health, and the Global Environment at Harvard T.H. Chan School of Public Health.
The cost of infectious diseases
3.3 million people are expected to die each year from viral zoonotic infectious diseases. The estimated value of these deaths is – at a minimum – $350bn with an additional $212bn indirect economic losses. This amount is based on lives lost from every new viral zoonosis—diseases that “spillover” into humans—since 1918.
According to the authors, preventing spillover at the source is rarely addressed when policymakers and multilateral organisations discuss pandemic risks – despite the fundamental role spillovers play in spreading emerging infectious diseases. To address this concern, the researchers recommended revising the World Health Organisation’s “phases of infectious disease emergence” to include a specific phase for spillover of infectious diseases from animals to humans.
“Resources placed into reducing deforestation are an investment to prevent future epidemics, but also to mitigate current threats, such as malaria and respiratory diseases associated with the burning of the forest,” said Marcia Castro, Andelot professor of demography and chair of the Department of Global Health and Population at Harvard Chan School. “Making these investments in prevention brings returns to human health, to the environment, and economic development.”
The study also addressed the emergence of novel and well-known pathogens and the researchers noted how additional actions could prevent further pandemics like avoiding carbon dioxide emissions, conserving water supplies, protecting Indigenous Peoples’ rights and conserving biodiversity. Furthermore, indirect damages which are not included in the cost estimates were factored in, such as psychological harms from lost jobs, lost relatives, or social isolation, delayed medical treatments, and loss or delays of education.
Primary prevention actions for future pandemics
The researchers recommended the following actions to prevent emerging infectious diseases from progressing into a pandemic.
- Better surveillance of pathogens that may spill from animals to people
A global viral discovery should be developed to target where prevention activities should be focused geographically. This library can help quickly identify pathogens when they emerge and accelerate our ability to develop tests and vaccines rapidly and deploy them widely.
More well-trained veterinarians are needed, especially in spillover hotspots, to monitor for emerging infectious diseases and prevent spillover from wildlife or livestock into people.
- Better management of wildlife trade and hunting
Inadequate monitoring and surveillance of the wildlife trade enable zoonotic disease emergence. An increased budget and personnel for the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the World Organisation for Animal Health, and national agencies charged with monitoring animal importation to conduct research, monitoring, and enforcement is necessary to reduce risky trade.
- Reducing deforestation
Deforestation, particularly in the tropics, brings people into contact with animals as they enter forests to clear them for agriculture or timber, build roads, or work in mines. It creates forest edges that facilitate contact between people and viral reservoir hosts.
Mitigating Amazonian deforestation is a cornerstone of primary pandemic prevention. Smaller forests are also important sources of emergent pathogens due to their proximity to densely populated settlements. Tying conservation measures to investments in healthcare system strengthening can support communities living in and around forests.
Agriculture must be reformed to minimise, or ideally reverse, land conversion, and demand for less sustainable food must also be curtailed.
In 2021, a task force led by Dr Bernstein found that the spillover of pathogens with the potential to cause pandemics to occur from livestock operations; wildlife hunting and trade; land-use change and the destruction of tropic forests; expansion of agricultural lands, especially near human settlements; and rapid, unplanned urbanisation. The report provided recommendations for research and actions to prevent new pandemics that have largely been absent from high-level discussions about prevention, including a novel call to integrate conservation actions with strengthening healthcare systems globally.
