There were no significant difference between disease groups and healthy control on either SARS-CoV-2-specific CD8+ T cell positive rate or fraction (Supplementary Table 8); By day 180, the detected positive rate and cell fraction of SARS-CoV-2-specific CD4+ and CD8+ T cells were close to that of day 90, with no significant difference between disease groups and healthy control, except for the detected positive rate of the SARS-CoV-2-specific CD4+ T cell in the cancer group at day 180 (81.8% versus 97.6% in health control, P = 0.0440), with significant lower than the health control. Here, CD4 is linked to cancer.