MAPT and Alzheimer disease: Another lesson learned by studying neurodegeneration in MS, AD and Parkinson’s disease (PD) that may bear insight in approaching Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is the relevance of assessing in the cerebrospinal fluid (CSF) inflammatory biomarkers (11) or other potential biomarkers for COVID-19 such as tau (77).