The objective of this sub-study was to compare the levels of neutralizing antibody (NAb), and specific CD4 and CD8 T-cell responses against SARS-CoV-2 WT and VOCs between vaccinated COPD patients and vaccinated healthy elderly subjects after receiving the second dose of ChAdOx-1/ChAdOx-1 homologous vaccination. This evidence concerns the gene CD4 and chronic obstructive pulmonary disease.