Then there’s the little-discussed question of whether testing plus contact tracing can actually be used to suppress a disease that has achieved community spread on a massive scale like the novel coronavirus. The combination is classically applicable in situations where there are handful of cases and the disease has not yet spread widely; that was the situation in South Korea where it seems to have been highly effective. The technique is also said to have proven effective in the 2014 Ebola outbreak. But the epidemiologistsI have spoken to about the novel coronavirus have not been able to provide a truly comparable case where testing and contact tracing reined in a disease that was this diffused across a huge geographical area.

Usually, when all other scenarios have been discussed, the topic turns to herd immunity. But as Bergstrom has been arguing for weeks, in practice that likely means a huge percentage of the population being exposed to the virus. Depending on the true case fatality rate, that could mean many millions of deaths around the world.

It’s time to start thinking about how we should react to this horrible scenario. It isn’t defeatism to ask what the world will look like if we lose the war we’re fighting. It’s realism.