Finally, P-selectin levels were significantly higher in the vaccinated post-COVID-19 patients, both females (2618.2 ± 1116.6 vs. 1497.2 ± 892.6 pg/mL, p = 0.043) and males (2339.6 ± 1122.1 vs. 1804.6 ± 1068.6 pg/mL, p = 0.034), after 5 months of diagnosis. The gene discussed is SELP; the disease is COVID-19.