Neither sunshine nor rain nor war, however, is truly infectious, not in the way a virus is, and this very important dimension is where personal-risk analogies start to tank. One person’s decision to eschew a seat belt, airbag, or life jacket rarely affects someone else’s fate. This language is very much in keeping with the United States’ pandemic response, which, as my colleague Ed Yong has written, prioritized individualism, exceptionalism, and free will. We turn to individualistic analogies because they are culturally salient. But they can end up being an “extreme mismatch,” Lewis told me: At heart, public health is a collective endeavor, from which no one is exempt.

I’ve seen attempts to course-correct. Twitter is rife with accusations that remaining unvaccinated is akin to drunk driving, smoking, or harming children. But these comparisons, while hinting at communal risk, can backfire. “We know that shaming of any kind just doesn’t work,” Cora Scott, the director of public information and civic engagement for the city of Springfield, Missouri, told me. Cast as enemies, people “shut down and stop listening,” Lewis said. Analogies like these also misportray the unvaccinated, many of whom haven’t been able to access their shots, or are still ineligible, or haven’t been given accurate information about the vaccine and the seriousness of COVID-19.

Scott, who leads vaccine outreach efforts in her community, told me she’s been favoring a different analogy: casting the spread of infection as fire, and humans as the kindling that the flames need to persist. I’ve tried this one myself, and vaccines fit in nicely, too. They’re sprays of flame retardant that can waylay fire on the move, while also shielding vegetation from the worst of the burn. The more trees are protected, the sooner the fire has nowhere left to go.