TNF and long COVID-19: Lastly, interleukins IL-1β, IL-6, and tumor necrosis factor plasma levels are elevated in PASC sufferers (Schulthei et al., 2022), and are also correlated to cognitive impairment in Alzheimer's disease (Silva et al., 2021), and with severity of hyposmia after COVID-19 (Liang et al., 2022).