Information about immunity to SARS-CoV-2, both in the context of COVID-19 disease pathogenesis and in the context of how to develop a good vaccine, remains limited. But developing a vaccine and predicting how the coronavirus pandemic will unfold until such a vaccine is available are both contingent upon the understanding of whether the immune system can mount a substantial and lasting response to SARS-CoV-2 and whether exposure to other, common, circulating coronaviruses provides any kind of protective immunity.