Previous studies identified toxic/metabolic encephalopathy as the most common neurologic complication in COVID-19.31 The observed relation between NfL and SOFA scores in our study and by others could argue in favour of this cause of NfL release.19 Another potential mechanism is that NfL increases are caused by axonal damage due to the inflammatory response of the brain to COVID-19. The gene discussed is NEFL; the disease is COVID-19.