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G iven widespread unreported SARS-CoV-2 infections, variable immunologic response based on host immunogenicity, vaccine type, viral strain, timing and sequence of vaccine or viral exposure, and humoral waning, the global SARS-CoV-2 immune landscape is largely unknown. Most countries launched national COVID-19 vaccination campaigns during early 2021, but few studies have characterized population-level immunologic responses to SARS-CoV-2, and fewer have aimed to translate findings to immunologic protection. Many large national seroepidemiologic studies were conducted in the pre-COVID-19 vaccine era and before emerging variants of concern, focusing primarily on seroprevalence (i.e., the presence or absence of SARS-CoV-2 antibodies) but not antibody levels (1-4). This focus was largely