Comparison of Four T-cell Assays and Two Binding Antibody Assays in SARS-CoV-2 Vaccinees With or Without Omicron Breakthrough Infection.

T-cell response assays show moderate to strong correlations, particularly when using the same platform. T-SPOT.COVID exhibits potential for estimating immune responses to the Omicron variant. To accurately define SARS-CoV-2 immune status, both T-cell and B-cell response measurements are necessary.