 While cross-reactive immunity between human coronavirus and SARS-CoV-2 may contribute to host protection, validating evidences are still scarce. Here the authors assess a cohort of 52 donors with immediate early contact with SARS-CoV-2 to correlate higher frequency of cross-reactive T cells with lower infection rate. This article was authored by Ria Kundu, Janakan Samnarian, Luli Wang, and others.