CD4 and COVID-19: To provide novel insight into the functionality of long-term SARS-CoV-2-specific memory CD4+ T (mCD4+ T) cells in recovered COVID-19 patients with or without vaccination, SARS-CoV-2-specific mCD4+ T (CCR7–, CD45RA–) cells positive for the intracellular cytokines TNF-α, IFN-γ and IL-4 were examined by a multiparameter ex vivo ICS assay.