Proponents of predictive initiatives say it’s too early to discount such approaches. If the same complaints had been raised in meteorology a century ago, “we wouldn’t have created the data that lets us forecast the weather, which we can do pretty well now,” says Jonna Mazet, the global director for PREDICT who also sits on the Global Virome Project steering committee.
“Can we predict pandemics? The answer right now is no. But just because something is hard to predict does not mean we cannot quantify its risk in a useful, actionable way—a logic that the insurance industry profits from,” adds Barbara Han, from the Cary Institute of Ecosystem Studies. No predictions are perfect, but at the very least, we can put boundaries on what is likely.
Resources aren’t infinite, though, and public health is an area that’s historically underfunded. Geoghagen argues that it would be best to channel efforts into approaches that would do the most good. For her, that involves looking at the “fault lines” where humans and animals meet—regions where people are more likely to be exposed to animal viruses because they are chopping down forests, or setting up dense animal markets, or hunting wild creatures for meat, or moving around a lot because of political instability.
Mazet agrees, and says that the Global Virome Project plans to look for viruses precisely at such fault lines. They want to, for example, search blood and meat samples of bushmeat, or the urine or saliva of rodents that share human homes. “It’s not aimed at detecting every virus out there,” she says, but she admits that the team hasn’t done the best job in explaining that to their fellow virologists.
But Geoghagen and Holmes argue that searching for these viruses in animals is still “a Sisyphean exercise.” You’d find too many, with no way of accurately assessing their risk of jumping into us. The project, they say, would be better off focusing on people—the workers in the bushmeat trade rather than the meat itself, for example. “Humans are the best sentinels: A virus discovered in humans very obviously can replicate in that host, which will not be the case for myriad viruses identified through biodiversity surveys of other [animals],” they say.
Andersen agrees. For the moment, preempting pandemics isn’t possible; what matters is catching them as early as possible. “Forget about detecting the virus before it jumps. Forget even about detecting the first patient,” he says. “Detect the first cluster of cases.” That’s possible if health workers routinely search for viruses in people who live at disease fault lines, and the advent of portable, pocket-size DNA sequencers could make such searches a reality.
These goals shouldn’t be seen in opposition, though. Kevin Olival from EcoHealth Alliance, who works with PREDICT, says that it would be impractical to study all fault-lines. “We need tools to help us narrow down and target our resources to the locations, host species, and viruses of greatest concern,” he says. Projects like PREDICT and the Global Virome Project may not act as crystal balls for future outbreaks, but they “help us prioritize on-the-ground disease surveillance.”
And PREDICT, through its work on detecting new animal viruses, has also helped to develop analytics tools and strengthen labs in developing countries, which will make it possible to do the kind of surveillance that Geoghagen, Andersen, and others are calling for. Everyone agrees that’s vital. “If we can’t even get routine surveillance working in hot-spot settings, we have no chance of getting something even more complex, like prediction, in place,” says Gardy.