TNF and COVID-19: In addition to the direct CNS invasion of the virus, CNS involvement in COVID-19 patients has also been linked to the induction of excessive cytokine secretion, which has also been perceived as a clue to the potential mechanism relevant to FSs in Omicron infection (38) and partially illustrated the higher levels of IL-6 and TNF-α revealed in the Omicron-FS group than in the Omicron-only and FS-only groups in our study.