The presence of CD4+ and CD8+ responses correlated with the proportion of IgG-s antibodies exhibiting neutralizing activity (OR [95% CI], 1.02 [1.01 to 1.03], p < 0.01) and the documented history of COVID-19 (66.7% in participants with vs. 47.3% in participants without a recorded history of infection). Here, CD4 is linked to COVID-19.