Breakthrough Covid, In Perspective

David Leonhardt: “The scale of breakthrough infections remains unclear. Are they a significant reason that cases are now surging in the U.S. — and a reason for vaccinated people to be concerned? Or are breakthrough infections rare exceptions that receive outsize attention?”

“Those are two very different scenarios. If breakthrough infections are an important source of Covid spread, it would suggest that vaccinated people should resume some of their previous precautions, like avoiding crowded places. If Covid is instead spreading overwhelmingly among the unvaccinated, it would suggest that the behavior of the vaccinated doesn’t matter very much; the only reliable way to reduce caseloads would involve more vaccinations.”

“I’m going to warn you up front that I don’t have a definitive answer for you.”