The last time I’d left the house was Friday evening, to pick up my son from the airport. He was returning from college out of state for spring break—maybe one that lasts until summer. As we wound up the dark freeway, he remarked at how normal everything seemed. The scene was not reminiscent of a zombie apocalypse, like in The Walking Dead, he told me, where you can see the danger and try to avoid it. For cities like Atlanta, in a state with more than 120 reported cases and counting, there’s enormous cognitive dissonance in avoiding an invisible microbe that’s spread, in part, by human hosts who exhibit no visible symptoms. The invisibility justifies, for some, adopting extreme caution or, for others, shunning that same caution—with no immediately apparent consequence either way.

Read: The dos and don’ts of ‘social distancing’

That lag explains the fear of overreaction: At best, hunkering down is inconvenient; at worst, for some, it’s impossible. Doing something different from the norm feels shameful—as does risking having gone too far in hindsight. But ultimately, the protective measures Americans are newly undertaking will always seem like overreactions, so long as they work. This is the paradox of the present moment: If we wait until the problem is sufficiently visible to transform overreaction into mere reaction again, we will have been too late.

In early 2014, a blizzard crippled Atlanta, where snow is rare, snow-clearing equipment is scant, and citizens don’t know how to drive in bad weather. The storm dropped an embarrassingly small measure of snow, perhaps a couple inches, and some people ended up stuck in freeway traffic for more than 18 hours. That time, the roads did look apocalyptic, just like a scene from The Walking Dead, in fact.

The storm only became a calamity because local officials didn’t plan for it in advance, and then responded poorly once the circumstances proved dire. The first mistake was failing to close schools and workplaces beforehand, when the storm was inbound. The second was releasing everyone at once into the weather when that first plan failed. In the years since, municipal officials and business leaders have learned their lesson: They delay or cancel work and school at even the slightest sign of possible winter storms. Knowing what could go wrong because it already did makes it easier to justify taking action that would otherwise seem like overreaction. The storm is like the zombies, now, made material in recent, living memory.

Compare that situation to the one COVID-19, the disease caused by this new coronavirus, presents. No example in recent history is analogous to the present moment. Those that feel similar, such as H1N1 in 2009 and Ebola in 2014, do so only because they are infectious diseases, not because their spread or their impact was similar to this one. COVID-19 is different: It spreads more rapidly, including via asymptomatic hosts. When it strikes hard, it can require ICU treatment, and enough of that demand at once can overwhelm hospitals, as Italy is experiencing.