Jeremy C. Young

The Imperial College team plugged infection and death rates from China/Korea/Italy into epidemic modeling software and ran a simulation: what happens if the US does absolutely nothing -- if we treat COVID-19 like the flu, go about our business, and let the virus take its course?

Here's what would happen: 80% of Americans would get the disease. 0.9% of them would die. Between 4 and 8 percent of all Americans over the age of 70 would die. 2.2 million Americans would die from the virus itself.

It gets worse. People with severe COVID-19 need to be put on ventilators. 50% of those on ventilators still die, but the other 50% live. But in an unmitigated epidemic, the need for ventilators would be 30 times the number available in the US. Nearly 100% of these patients die.

So the actual death toll from the virus would be closer to 4 million Americans -- in a span of 3 months. 8-15% of all Americans over 70 would die.

How many is 4 million people? It's more Americans than have died all at once from anything, ever. It's the population of Los Angeles. It's 4 times the number of Americans who died in the Civil War...on both sides combined. It's two-thirds as many people as died in the Holocaust.

Americans make up 4.4% of the world's population. If we extrapolate these numbers to the rest of the world (warning: MOE is high here), this gives us 90 million deaths globally from COVID-19, in 3-6 months. 15 Holocausts. 1.5 times as many people as died in all of World War II.

Now, of course countries won't stand by and do nothing. So the Imperial College team ran the numbers again, this time assuming a "mitigation" strategy: all symptomatic cases in the US in isolation. Families of those cases quarantined. All Americans over 70 social distancing.

This mitigation strategy is what you've seen a lot of people talking about when they say we should "flatten the curve": try to slow the spread of the disease to the people most likely to die from it, to avoid overwhelming hospitals.

And it does flatten the curve -- but not nearly enough. The death rate from the disease is cut in half, but it still kills 1.1 million Americans all by itself. The peak need for ventilators falls by two-thirds, but it still exceeds the number of ventilators in the US by 8 times.

That leaves the actual death toll in the US at right around 2 million deaths. The population of Houston. Two Civil Wars. One-third of the Holocaust. Globally, 45 million people die: 7.5 Holocausts, 3/4 of World War II. That's what happens if we rely on mitigation & common sense.

Finally, the Imperial College team ran the numbers again, assuming a "suppression" strategy: isolate symptomatic cases, quarantine their family members, social distancing for the whole population, all public gatherings/most workplaces shut down, schools and universities close.

Suppression works! The death rate in the US peaks 3 weeks from now at a few thousand deaths, then goes down. We hit but don't exceed the number of available ventilators. The nightmarish death tolls from the rest of the study disappear.

But here's the catch: if we EVER relax suppression before a vaccine is administered to the entire population, COVID-19 comes right back and kills millions of Americans in a few months, the same as before.

After the 1st suppression period ends in July, we could probably lift restrictions for a month, followed by 2 more months of suppression, in a repeating pattern without triggering an outbreak or overwhelming the ventilator supply. Staggering breaks by city could do a bit better.

But we simply cannot EVER allow the virus to spread throughout the entire population in the way other viruses do, because it is just too deadly. If lots of people we know end up getting COVID-19, it means millions of Americans are dying. It simply can't be allowed to happen.

How quickly will a vaccine be here? Last week three separate research teams announced they had developed vaccines. Yesterday, one of them (with FDA approval) injected its vaccine into a live person, without waiting for animal testing. That's an extreme measure, but necessary.

Now, though, they have to monitor the test subject for 14 months to make sure the vaccine is safe. This part can't be rushed: if you're going to inoculate all humans, you have to make absolutely sure the vaccine itself won't kill them. It probably won't, but you have to be sure.

Assuming the vaccine is safe and effective, it will still take several months to produce enough to inoculate the global population. For this reason, the Imperial College team estimated it will be about 18 months until the vaccine is available.

During those 18 months, things are going to be very difficult and very scary. Our economy and society will be disrupted in profound ways. And if suppression actually works, it will feel like we're doing all this for nothing, because infection and death rates will remain low.

It's easy to get people to come together in common sacrifice in the middle of a war. It's very hard to get them to do so in a pandemic that looks invisible precisely because suppression methods are working. But that's exactly what we're going to have to do. /end

A couple of clarifications/corrections. 1) An error on my end: 45 million global deaths would be the most from a pandemic since the Spanish Flu of 1918, not since the Middle Ages. Apologies for the mistake.