No one, it seems, can agree on the immunological exchange rate—whether a past infection can sub in for one inoculation or two inoculations, or more, or none at all—or just how much immunity counts as “enough.” Even among the nation’s top health officials, a potential shift in the social status of the once-infected remains “under active discussion,” Anthony Fauci, President Joe Biden’s chief medical adviser, told me. For now, though, he reiterated, “it still is the policy that if you’ve been infected and recovered, that you should get vaccinated.”