GFAP and influenza: The neuroinflammatory marker glial acid fibrillary protein (GFAP) has been found to be increased in the acute phase of COVID-19 [112,113] but, according to one study on 175 COVID-19 patients and 45 patients with influenza, levels return to their normal baseline 3 months after infection, and importantly are not different compared to samples with influenza [113].