With these results, we can state that it was possible to detect biochemical changes through FTIR spectroscopy associated to COVID-19 immune response in vaccinated people, once IgG, IgA, IgM, as well as different cytokines, such as IFN-γ, TNF-α, IL-1 β, IL-6, and IL-10, were detected, highlighting that the concentration of the studied molecules expressed a higher content in the V-COVID-19 group than the V-Healthy group, showing statistical significance. This evidence concerns the gene IL6 and COVID-19.