The anxiety about how people might behave when they are less afraid is all too familiar to those of us who work on HIV prevention. When the medication Truvada was approved in 2012 as preexposure prophylaxis (or PrEP)—a daily pill to prevent HIV—it sparked a debate about what public-health experts call risk compensation. The worry was that people who felt protected by PrEP would use condoms less often—potentially negating the medication’s effect and increasing their risk of contracting other sexually transmitted infections. PrEP has turned out to be far more effective at preventing HIV than condoms are, assuaging some of those concerns. But the emphasis on risk compensation was not solely about infection. True to America’s puritanical roots, it also reflected moral judgments about condomless sex; PrEP was described as a “party drug” and its users were called “Truvada whores.” That stigma has been profoundly detrimental: Uptake of PrEP remains low, and some clinicians still hesitate to prescribe it, especially to people who use condoms inconsistently and therefore need the medication most.

Moral panic about risk compensation is misguided; it obscures the reasons some people change their behavior and what they could lose by not doing so. For some, the ability to have more physical intimacy is the whole point of PrEP—just as it is, for some, the whole point of birth-control pills. Likewise, some people are eager to get a coronavirus vaccine because they feel an intense need to be close to others. That’s why exhortations about unwavering vigilance after vaccination may have unintended consequences—not just dissuading vaccine uptake but also sapping the public’s hope. “The truth is that if I thought I was going to be living the way I’m living now for another 10 months,” the New York Times columnist Michelle Goldberg tweeted about the dour vaccine messaging, “I’d probably give up completely.”