And so we are rapidly shutting down routine care. We have canceled all planned follow-ups with patients with diabetes and heart failure at this point because we have to preserve that personal protective equipment.

Read: Why the coronavirus has been so successful

Foer: So what are you seeing now?

Horn: All over Boston, we’re hearing reports that the number of visits with possible coronavirus cases has started to hit that exponential-growth trend. We were at 10 to 15, recently up to 30 to 40, and now yesterday there were some 129 visits or something like that at our surge-testing clinic.

Foer: I know you’ve been following the course of the disease in Italy …

Horn: That really set off the alarm bells. We began hearing earlier last week about wide-scale ethical dilemmas: Italian physicians having to choose which patient receives a ventilator. And the rapidity with which we heard that patients can’t get basic access to inpatient or outpatient care in Italy raised the concern that we weren’t even thinking about the pace and [overwhelming of the system] that coronavirus can cause.

Foer: Could the crisis here land even harder than in Italy?

Horn: I have to say that Boston is one of the places that did take rapid and important action last week, such as delaying the Boston Marathon, closing Boston public schools, canceling our Saint Patrick’s Day parade. But as I walked around my neighborhood here yesterday, I was shocked and concerned to see that our coffee shops were full of people, our restaurants were full of people having drinks and enjoying their time together. And it just showed me that I am carrying a burden of seeing what we’re doing at the hospital, seeing how concerned we are about what we know is coming. But my fellow citizens don’t see it. My personal psychic crush is that I’ve been walking around for the last week seeing what’s coming and feeling somehow unable to share that clearly and effectively with friends, family.

Read: How the coronavirus became an American catastrophe

Foer: How close are we to zero hour? If we don’t do extreme social distancing in the next day or two, what do you think Boston hospitals are going to start to see?

Horn: What we’ll start to see are primary-care practices jammed up with calls, because calls with worried patients take a really long time. Then the really worried, scared patient that doesn’t get through will unnecessarily go to the emergency department, which is already full. That clearly will create a major strain on emergency-department management systems.

And then the hospital fills with older patients with coronavirus with low oxygen levels that need oxygen support and IV fluids and help with nutrition. Suddenly we have multiple floors of those patients filling up beds. And then 15 percent of them begin to crash and develop acute respiratory distress requiring mechanical ventilation to save their life—all at the same time—and then we don’t have enough ICU beds and mechanical ventilators to manage the patients that are all crashing at the same time. We will be [grappling with] the types of ethical dilemmas that we really only see in wartime in this country.