CD4 and infection: Effective control and protection from less severe disease has been associated with SARS-CoV-2 specific CD4+ type 1 and follicular helper T cell responses,53 and a coordinated CD8+ type 1 effector response, whereas the role of other CD4+ helper subsets (type 2, type 17) are unclear.120 129–131 Memory responses after infection and vaccination are characterised by an effector memory CD45RA+ response, although this memory phenotype was largely absent in individuals who were infected after vaccination.93