If we cannot resume economic activity without causing a resurgence of Covid-19 infections, we face a bleak and unpredictable future of opening and closing schools and businesses.
We can find a way out of this dilemma by exploiting a key property of the virus: its latency period: the average delay of three days between the time a person becomes infected and the time they can infect others.
People can work two-week cycles, on the job for four days, and by the time they become infectious, 10 days at home locked up. The strategy works even better when the population is divided into two groups of households that work alternate weeks.
Austrian school officials will adopt a simple version, with two groups of students attending school for five days every two weeks, starting May 18.
The models we created at the Weizmann Institute in Israel predict that this two-week cycle can reduce the number of replication of the virus, the average number of infected people for each infected person, below one. Therefore, a 10-4 cycle could suppress the epidemic while allowing for sustainable economic activity.
Even if someone is infected and symptom-free, he or she would be in contact with people outside of their home for only four days every two weeks, not 10 days, as with normal hours. This strategy has another impact: it reduces the density of people at work and school, which reduces the transmission of the virus.
Schools can have students attend for four consecutive days every two weeks, in two alternate groups, and use distance learning methods on the other school days. Children would go to school on the same days that their parents go to work.
Companies would work almost continuously, alternating between two groups of workers, for regular and predictable production. This would increase consumer confidence, underpinning supply and demand simultaneously.
During closing days, this approach requires adherence only at the distance level that has already been demonstrated in European countries and New York City. Avoid the economic and psychological costs of opening the economy and then having to reestablish total blockage when cases inevitably resurface. Giving hope and then taking it away can cause despair and resistance.
A 10-4 routine provides at least one part-time job for millions of people who have been fired or sent on leave without pay. These jobs avoid the devastating, often lasting, mental and physical effects of unemployment. For those living on cash, there would be four days to earn a living, reducing the financial need to completely ignore the blockade. Commercial bankruptcies would also be reduced, accelerating the eventual economic recovery.
The cyclical strategy is easy to explain and enforce. It is fair in terms of who can return to work. It applies to any scale: a school, a company, a city, a state. A region that uses the cyclical strategy is protected: infections that come from abroad cannot spread widely if the number of reproduction is less than one. It is also compatible with all other countermeasures being developed.
Workers can and should wear masks and spacing while working. However, this proposal is not based on large-scale evidence, which is not yet available in all parts of the United States and may never be available in large parts of the world. It can be started as soon as a steady decrease in cases indicates that the block has been effective.
The cyclical strategy should be part of a comprehensive exit strategy, which includes the self-quarantine of those with symptoms, location and isolation of contacts and protection of risk groups. The cyclical strategy can be tested in limited regions during specific trial periods, even one month. If infection rates increase, it can be adjusted to fewer work days. Conversely, if things go well, additional work days can be added. In certain scenarios, just four or five days of blocking in each two-week cycle could still prevent a resurgence.
The coronavirus epidemic is a formidable enemy, but it cannot be beat. By scheduling our activities intelligently, in a way that takes into account the intrinsic dynamics of the virus, we can defeat it more quickly and accelerate a full return to work, school, and other activities.
Uri Alon and Ron Milo are professors of computational and systems biology at the Weizmann Institute of Science in Israel. Eran Yashiv is Professor of Economics at Tel Aviv University and at the Macroeconomics Center of the London School of Economics.
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