IL17A and COVID-19: Although the microbial exposures included in our dataset concerned non-pathogenic bacteria, overrepresentation analysis of the genes of which the variance was explained to a considerable extent by “Microbiome” revealed pathways related to host–pathogen interactions, such as “Kaposi sarcoma-associated herpesvirus infection”, “COVID-19”, “hepatitis B and C”, “Influenza A” and “IL-17 signaling pathway”.