Mathematical Model for Virus Exit Strategy.

Think of dieting: you can fast for about two months and lose lots of weight, but you probably will die--and, even if you survive, you quickly will put back on the pounds. Similarly, a two-month lockdown will suppress the coronavirus, but it will kill the economy. Lockdown will push hundreds of millions of people into unemployment and poverty. Many sectors of the economy will collapse. At the end of each lockdown, remaining patients will cause a resurge in the epidemic, forcing another lockdown.

This is the well-known yo-yo effect, with the number of coronavirus patients going up and down. At the same time, the global economy will be hit hard and millions will go hungry. When the dust settles, more people will have died of hunger than of coronavirus.

Uri Alon, a professor and systems biologist at the Weizmann Institute of Science, Rehovot, Israel, and his graduate students Omer Karin and Yael Korem-Kohanim, together with senior engineer Boaz Dudovich of Applied Materials, suggest, based on an epidemiological model they developed, a policy that effectively suppresses the coronavirus and, at the same time, allows sustainable, albeit reduced, economic activity.

The model is based on intermittent lockdown: five days of lockdown and two days of work every week. In this way, the virus replication number (the amount of people infected by each...