In addition, although in agreement with Sekine et al.18, we found that some polyfunctional T cells were detectable in close contacts, cells producing both IFNγ and TNF appear largely specific for infected patients rather than for close contacts and healthy donors, suggesting that for COVID-19 patients, the occurrence of stronger antigen stimulation and greater inflammation during viral infection led to an enhanced polyfunctional T-cell response. Here, IFNG is linked to viral infectious disease.