From internet comments I’ve seen some confusion on the suppress then “test, trace, isolate” strategy. The “flattening the curve” metaphor suggested that lockdown was all about spreading infections over time to keep the medical system operational. But more importantly, the purpose of lockdown is to reduce the infection rate, R, below 1. A virus needs hosts. Take away the hosts and it fades away. We can take away hosts by making people immune, either with a vaccine or through surviving exposure. We can also take away hosts by hiding–that’s what lockdown is for. If enough people hide, then the virus burns out and fades away.
Of course, hiding leaves us vulnerable to multiple rounds of infection. That’s where the second part of the strategy, test, trace and isolate comes into play. When the infection is running wild, as it is now, we don’t have enough tests to keep up with the virus. But after suppression we can put test, trace and isolate into effect very quickly as outbreaks flare up but before the virus runs out of control again. Increasing our test capacity dramatically makes this strategy even more viable. Thus, as V.V. Chari and Christopher Phelan write in a good op-ed:
…A wise use of the breathing room provided by mass quarantines would be to put in place the infrastructure to allow us to mimic the policies of countries such as South Korea, Taiwan, Singapore and Hong Kong. These countries have thus far controlled the pandemic at much lower economic cost…[using] aggressive but targeted quarantine policies. They quarantine people displaying symptoms, aggressively trace the people they have contacted, test their contacts, and then quarantine those who have the virus (and sometimes those who have just had contact with those who test positive), regardless of whether they are symptomatic or not.
It is a test, trace and isolate policy. These countries have not generally engaged in mass quarantines or shut down factories, shopping malls or restaurants.
After suppression, we can combine “test, trace and isolate” with mask wearing and other safety protocols and move towards reopening the economy.