This is great and all, but I'd be interested what proportion of the entire cohort demonstrated a T-cell immune response, not just the 100 who tested sero-positive for SARS-COV-2. There is growing speculation that a significant minority of people may mount a T-cell immune response without ever contracting SARS-COV-2 itself, based on exposure to other coronaviruses. This would be great news since it further reduces the effective threshold for endemic equilibrium.