As a previous study revealed that 82 COVID-19 convalescents showed a positive IFN-γ response to the spike peptide pool (Cassaniti et al., 2021), in our study, we also found that all one-month COVID-19 convalescent PBMCs responded to alpha and delta variants spike peptide pool stimulation and produced IFN-γ and IL-2 (Figures 1G, H), indicating that these individuals generated cellular immune memory against SARS-CoV-2. Here, IL2 is linked to COVID-19.