In this analysis, we planned to estimate the rates of not achieving a robust/above-average humoral response to COVID-19 mRNA vaccines in PLWH who received ≥2 doses, using two different endpoints indicative of the CoP/in-laboratory average response derived from binding antibodies, and to investigate the role of CD4 and the CD4/CD8 ratio in predicting a humoral response in this setting. The gene discussed is CD8A; the disease is COVID-19.