Coronavirus infections are happening among vaccinated people. They’re going to keep happening as long as the virus is with us, and we’re nowhere close to beating it. When a virus has so thoroughly infiltrated the human population, post-vaccination infections become an arithmetic inevitability. As much as we’d like to think otherwise, being vaccinated does not mean being done with SARS-CoV-2. Post-vaccination infections, or breakthroughs, might occasionally turn symptomatic, but they aren’t shameful or aberrant. They also aren’t proof that the shots are failing. These cases are, on average, gentler and less symptomatic; faster-resolving, with less virus lingering—and, it appears, less...