Apologies for the macabre subject, but with everyone freaking out about the coronavirus, I’m wondering if it makes sense to step back and ask why the Diamond Princess wasn’t a worst-case scenario. The ship held 3,700 people. The virus spread all around the ship before anyone knew what was going on. Then everyone on board was kept on board, all breathing from the same ventilation system, eating food from the same kitchen (almost surely prepared by at least some workers who had the virus, but didn’t know it). Out of 3,700 passengers and crew, 6 have died (Business Insider).

That’s a death rate of 1/6th of 1 percent (0.16 percent), and concentrated among people whose immune systems were weakened due to other factors (i.e., people who might have died a year later from the flu).

The U.S. overall is not more crowded than a cruise ship. Why should we expect more than 0.16 percent of Americans to die when this is all over? That’s unfortunate, of course, and a huge number when multiplied by 330 million: 535,000. But it is not an economy-ending or country-ending number. And, since our country is not in fact as densely populated as a cruise ship, the real number might be far less than this upper bound. It might be closer to the 80,000 who died from the flu in 2017-2018 (source). And there might not be that many additional deaths because the same people who get killed by the flu are also susceptible to COVID-19.

One factor that could explain how the death rate could be higher: as the disease spreads, hospitals and other health care resources will be spread thin. But, on the other hand, knowledge about how to treat the infection will improve. If these two factors cancel out, we’re back to the Diamond Princess being the worst-case scenario. Finally, consider that the cruise ship demographic is older and more fragile than the general population.

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