Nobody wants to return to the full-scale open-ended shutdowns of the early days of the pandemic. And yet muddling forward is not working. As a compromise, some European leaders have embraced the idea of “circuit breakers” — fairly intense closures lasting a limited time — that would interrupt viral spread and bring case counts down without the long-lasting social and economic pain of extended lockdowns. Britain’s Labour Party leader, Keir Starmer, has called for a circuit-breaker of two to three weeks, for example, to prevent a “sleepwalk into … a bleak winter.” Circuit breakers can be one-off interventions or regular occurrences (say, a three-week “reset” every two months).
The case for circuit breakers rests in part on the failures of our current approach. Phased reopenings aim to allow as much activity as possible, consistent with keeping cases at controlled levels through social distancing, masking and other restrictions. But they have a number of disadvantages in practice. First, they are hard to maintain over extended periods as compliance fatigue sets in, standards relax — and cases tick up. Furthermore, disparities in infection rates, both between and within states, make sacrifice inefficient. Many towns and subpopulations have already sacrificed more than enough to eliminate internal spread, but a constant threat of outside reinfection prevents them from relaxing and enjoying their triumph.
The underlying idea of the circuit breaker approach makes intuitive sense: After cutting oxygen off from a fire to reduce it to embers, for instance, restoring airflow intermittently doesn’t produce large flames. But add a steady continuous oxygen supply, even at a low level, and the blaze quickly rages out of control.
One study making use of epidemiological models — as yet, not peer-reviewed — found that a two-week circuit breaker would halve the number of deaths in the United Kingdom between now and the end of the year. And our own preliminary research suggests that if society wants to allow a certain amount of social and economic activity, doing so within select windows, followed by short-term shutdowns, will lead to fewer cases than allowing the same amount of activity to occur across unbroken stretches of time.
Using mathematical techniques, our work explored questions like this one: Suppose a town wishes to allow 1,000 small but risky activities like haircuts, ballgames, academic classes and small social gatherings over the course of a month. Is it better to put all the activities in one half of the month or space them out evenly? The mathematical answer is that concentrated sacrifice, followed by a period of relative openness, beats sacrifice that is spread out consistently over time. The size of the impact depends on many factors, but a typical analysis finds that 10 to 20 percent more activity might be possible (for the same amount of disease spread) when the activity is more concentrated.
Of course, not all activities can be shifted in time, so necessary events like urgent medical procedures would continue during a circuit-breaker shutdown. Additionally, when a month of activity