Possible reasons why some infected individuals have low overall adaptive immune responses could be due to (i) lower initial viral loads during first wave infections compared to later waves of variants (85); and (ii) possibly having more inhibitory and/or exhausted B and T cells (24); but lower RBD-specific responses could result if antigen presentation to CD4 T cells is dominated by epitopes in spike fragments outside of RBD (65, 86). This evidence concerns the gene CD4 and infection.