CD4 and infection: May the predominant mediator of immunity following decay of neutralizing antibody titers (407) and across pre-Omicron variants (407); S-specific CD8+ and CD4+ central and effector memory T-cells also shown to be likely predominant in vaccine-mediated immunity against Omicron variant (195); increase in proportion of CD4+ TH17 central memory cells seen at least 24 weeks post-infection (406)