TNF and COVID-19: In future studies, it would be useful to evaluate the correlations between olfactory scores and both serum and mucus levels of other pro-inflammatory cytokines such as IL-10, IL-12, IL-15 and TNF-α which are secreted by cells infected with SARS-CoV-2 [37] and involved in the cytokine storm at the base of the most severe cases of COVID-19 [38].