To prevent a dangerous new virus from having its way with humankind, you might take a page from the Chinese warrior king Sun Tzu, and think like the enemy.
Imagine you are a coronavirus, in a form never before seen by humans. Your goal is simple but wildly ambitious: invade and hijack the cells of a new host and multiply for as long it takes to establish your spawn in at least one other new host.
Repeat until there are no humans left to infect.
Since its emergence in Sun Tzu’s homeland, the coronavirus known to scientists as SARS-CoV-2 has gone about its task with vigor and success. It has jumped national borders with ease, infecting more than 9 million people around the world and killing at least 470,000 in about seven months. The roughly 7.7 billion people who have evaded infection so far seem to be squarely in its sights.
But humankind has a few tricks of its own.
In fits and starts, public health officials have mustered their citizens to shun the kinds of gatherings that provide a virus rich opportunities to spread. Scientists have peered into the coronavirus’s genome to unlock secrets about where it came from, how it has evolved and what it will take to thwart it.
Now it’s a race to see which side gains the upper hand.
Viruses are not as smart as humans, but they are much more patient, said Harvard University epidemiologist William Hanage. And this virus’s track record does not bode well for a strategy of ignoring it in hopes it will burn itself out, he added.
“That would be waiting for the virus to help us,” Hanage said. “That’s not a good idea.”
The imperatives of survival make a successful virus an unpredictable guest — cruel to some, kinder to others, and capable of evolving new strategies as its pool of potential targets thins.
“There’s no reward for a virus lineage to be easy on its host,” said Frederick M. Cohan, an evolutionary biologist at Wesleyan University.
It must not kill him immediately, as many early forms of the Ebola virus did to their victims. Such outbreaks are destined to fizzle.
But a successful virus is fine with leaving its victim a depleted shell, Cohan said: As long as it has succeeded in making him sick enough to draw others to his bedside where they’re exposed to his bodily fluids or respiratory droplets, it will live to infect another victim.
It need not be choosy about its victims, at least initially. It can spare the young and healthy and go after the weak and infirm first, as the coronavirus appears to be doing.
But experts believe that a virus that stands the test of time will ease up as its potential hosts dwindle and public health precautions take hold.
