Three weeks ago on these pages, my colleague V.V. Chari and I asserted that a limited mass quarantine period would make sense only if we used the time it bought us to radically change the facts on the ground regarding our ability to test and trace.
Thankfully, it appears our state has indeed used this time to increase its ability to test, trace and isolate.
But we also warned that at the end of any time-limited mass quarantine, we would still be almost where we started — with a small fraction of the population infected and able to infect almost everybody else — and thus facing extension of our mass quarantine.
What are the benefits of continuing our lockdown (albeit as slightly relaxed last week)? I see three.
One benefit is we are buying time to develop an effective vaccine or treatment. But should we be confident such a reprieve is coming any time soon? The number of times humankind has created an effective vaccine against any coronavirus currently stands at zero. While some antiviral treatments have shown promise, hopes that a "magic bullet" treatment is soon forthcoming are exactly that — hopes.
A second benefit is that "flattening the curve" through a prolonged shutdown can change the fraction of us who will eventually get this disease even without a vaccine. But this effect is smaller than one might guess.
Absent a vaccine, the epidemiology models governments currently use predict that unless we take extreme mitigation measures forever, at least 60 to 70% of us will eventually get this disease. Long-term shutdowns can change how high a fraction above this 60 to 70% eventually get infected, but not the fact that the majority of us will get infected.
A third benefit of a prolonged shutdown is that it is certainly better to get COVID-19 (or cancer, or a heart attack, or a stroke) when the hospital system is not overwhelmed. Yet in part due to many truly heroic efforts of our medical community, our system has not been overwhelmed, and other than in New York City, has not been close to being overwhelmed.