The investigators will compare study parameters (basal) between mild-moderate and severe COVID-19 patients and with other study groups (i.e. convalescent and healthy controls). Nasopharunx microbiota dysbiosis, in vitro cytokines production profile, and peripheral blood flocytometric results of the four study groups will be compared.~In vitro cytokines production will be studied and compared in Nill (No antigens) and Mitojen (Cocktail of antigens) pre-prepared test tubes.
The investigators will study nasopharunx microbiota composition, RNA sequences and in vitro cytokines production by peripheral blood cells of COVID-19 patients (both mild-moderate and severe cases) (comparing with convalescent patients and healthy controls).