The Global Battle to Force the Coronavirus Below Its Tipping Point
When the virus’s reproduction number is above 1, it spreads. Below 1, it fades away.
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The difference between a global pandemic and a short-lived outbreak is the number 1. That’s the tipping point of epidemiology. If each case of the novel coronavirus from Wuhan, China, leads to more than one additional infection, the disease will continue to spread. If each case leads to less than one additional infection, it will stop spreading and then slowly but surely fade away. It’s that simple.
Almost everything being done to fight the new virus—the face masks, quarantines, travel limitations, crash development of a vaccine—can be thought of as part of an effort to push the “reproductive number” of the virus from above 1 to below that tipping point.