Scientists estimate that two new viruses leap from animals to humans each year — the most recent and famous being the novel coronavirus. Scientists call this process “spillover,” and research published Thursday in the journal Science reviews ways to prevent it.
Researchers suggested a handful of preventive strategies, including changes to the wildlife trade and farming practices, as well as better early detection of disease outbreaks. But one idea stands out, says co-author Aaron Bernstein, who runs Harvard’s Center for Climate, Health and the Global Environment.
“I think in terms of bang for your buck, it's deforestation,” Bernstein says. “Protecting forests gives you a whole suite of benefits, on top of the potential to reduce the risk of spillover.”
Humans and livestock interact with wild animals more often along the edges of cleared forest, making spillover more likely. And, says Bernstein, preserving forests also protects water supplies, discourages wildfires, and increases carbon dioxide storage, which can slow climate change.
The study notes that “the clear link between deforestation and virus emergence suggests that a major effort to retain intact forest cover would have a large return on investment, even if its only benefit was to reduce virus emergence events.”
The study authors propose spending up to up to $9.6 billion a year to reduce deforestation. They also propose spending on other measures, including about $500 million a year to expand wildlife-trade monitoring programs, between $217 and $279 million annually on early disease detection and control measures, and more than $19 billion each year on programs to end the wild meat trade in China.
The price tag for all the proposed prevention strategies comes in at $18 to $27 billion per year. That sounds like a lot, but implementing them for ten years would add up to only about 2% of the costs of the COVID-19 pandemic so far — an estimated $2.6 trillion already lost, as well as more than 600,000 deaths worldwide.
“The benefits of stopping pandemics before they start could be enormous,” note the study authors. Or as Bernstein puts it: “Salvation comes cheap.”