IFNG and COVID-19: Lastly, the Alleles-1/2 group (heterozygous) showed only a negative correlation between serum IgG levels for SARS-CoV-2 antigens (IgG-COVID-19) and the percentage of intermediate monocytes at the pre-vaccination time point and positive correlations between the systemic levels of these antibodies (IgG-COVID-19) and the circulating levels of IL-10 and IFN-γ, at the post-vaccination time point.