Preventing spillover of viruses from animals to humans would only cost 5% of the losses they cause, claims report

An investment of €18 billion a year would prevent 1.5 million deaths worldwide, according to a study that highlights the importance of hiring more veterinarians as ‘watchmen’ for new pathogens

A German scientist takes samples from the carcass of a wild duck to test for bird flu.
A German scientist takes samples from the carcass of a wild duck to test for bird flu.Carsten Koall (Getty Images)
Javier Salas

The ongoing Covid-19 pandemic is far from being a unique event. Ebola, MERS, Zika, bird flu… Viral pathogens are spilling over to the human population at an ever-increasing rate, causing more serious and more widespread global epidemics. In the last 50 years, an average of 3.3 million people have died every year due to viruses that originated in animals – a figure that was calculated before Covid and that was already on the rise. Not nearly enough is being done to stop this spillover – that’s according to a study from 20 or so specialists, who are also proposing a formula so that lawmakers can see that it is worth the effort to try.

This would be an extraordinarily profitable investment: a complete and global plan to stop the propagation of these viruses from fauna to people would cost no more than 5% of the losses that they cause each year. “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,” said via a press release Aaron Bernstein, a Harvard researcher and the main author of the study, which was published in Science Advances.

An ever-greater and ever-more-connected human population is constantly creating more opportunities for viruses to propagate once they become established among human populations, explains another coauthor of the study, Andy Dobson from Princeton University. “This strongly suggests that we need to focus more on preventing pathogens crossing over, than on stopping them spreading once they have established,” Dobson explains via email conversation with EL PAÍS. “The impact of Covid-19 on the economies and mortality rates of many countries illustrates that prevention is significantly more effective than cure.”

This team of experts offers a conservative estimate that the world spends around €300 billion due to deaths and around €185 billion in direct economic losses due to emerging zoonotic diseases. And that is despite the fact, as the authors admit, that they are not able to include all of the factors given the difficulty of estimating the psychological impact, the educational burden of an entire generation and the additional costs caused by delayed medical attention due to the pandemic.

Slaughtered bats at a market in Indonesia.
Slaughtered bats at a market in Indonesia.Universidad de California Davis

To deal with these huge numbers, the investment in efficient preventive measures that would limit infection among humans with these illnesses would, according to the researchers, be around €18 billion. This figure would serve to reduce the number of deaths by half at least. “The net annual cost of putting in place mechanisms to significantly reduce risk of spillover are consistently less than the average annual cost of outbreaks,” Dobson explains via email. “There are consistent economic and environmental benefits from putting into place mechanisms that reduce spillover rates.” “Even a 1% reduction in risk of viral zoonotic disease emergence would be cost-effective,” says the study.

According to the investigation, there are three primary mechanisms that allow for pathogens to spill over to human populations: tropical deforestation, which is closely related to livestock and agricultural intensification; trade in wildlife; and the lack of resources for detecting these viruses before the health emergency takes hold. And that is where action is needed. “Viruses are detected in humans at a roughly uniform rate of two novel species per year,” the study warns, adding: “Humanity needs a global viral discovery project if we are to prevent future pandemics.”

We need to focus more on preventing pathogens crossing over, than on stopping them spreading once they have established
Andy Dobson from Princeton University

“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, in the aforementioned press release. “Making these investments in prevention brings returns to human health, to the environment, and to economic development,” she added. What’s more, a wealth of jobs can be created in a variety of fields as the global economy is reconfigured due to the pandemic.

The report begins by criticizing the fact that leaders and policymakers “only take actions after humans get sick.” “We sharply disagree,” say the authors. They argue that the spillover of viruses from animals to humans is the main source of risk when it comes to pandemics. “Hence, the failure to consider minimizing spillover in influential conversations dedicated to preventing the next pandemic perplexes us.” Specifically, the report takes issue with the Global Preparedness Monitoring Board, a joint initiative of the World Bank and the World Health Organization (WHO), and which was created after the ebola epidemic. Its reports and strategies do not mention how to prevent spillover.

In view of this, one of the most important measures that should be taken is the hiring of many more people in the veterinary field, because they have an essential role as “watchmen” for the appearance of new illnesses. And, as the study points out, they have been among the main defenders of the concept of “One Health,” which integrates human and animal wellbeing in general, and infectious diseases in particular. However, they are rare, in particular in countries and regions at greatest risk. “A country with few veterinarians, many reservoir species, and many people who consume or trade wildlife will be at greater risk for zoonoses,” the authors state.

Scientists are investigating the spillover of viruses in animals such as bats.
Scientists are investigating the spillover of viruses in animals such as bats.Gianluca Battista

Virologist Marion Koopmans, who was part of the mission to find the origin of the Covid-19 pandemic in Wuhan, China, believes that this work is an “interesting argument for focusing more on true prevention: trying to reduce outbreaks at their origin,” given that the majority of the initiatives for preparing pandemics “are focused on the detection of human illnesses, but that is putting the cart before the horse.” However, her colleague Alina Chan, who defends the possibility that SARS-CoV-2 escaped from a laboratory, criticizes the fact that in the past, these specialists would carry out research in an opaque manner and are not now “explaining exactly how they will work to improve security and transparency of the work to discover viruses.”

“Solving these problems mainly requires political will and international collaboration and cooperation,” explains Dobson. According to this specialist, “increasing the number of trained veterinary staff throughout the world will hugely increase the productivity of global agriculture and establishing a global database of viral diversity will allow more rapid development of tests and vaccines for future outbreaks.”

As was said in 2007 by Michael Leavitt, the then-US Secretary of Health and Human Services: “Everything we do before a pandemic will seem alarmist. Everything we do after will seem inadequate.” Apart from the fact that they serve to put the lessons learned into action.

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