In addition, longitudinal and cross-sectional and case-control studies assessing pairwise cognitive and olfactory performances in conjunction with classical biomarkers (Aβ 1–42, phosphorylated tau, and NfL) in CerebroSpinal Fluid (CSF) or plasma from patients recovering from neurological sequelae of acute COVID-19 are needed in the near future to understand whether the chronic anosmia with olfactory deterioration actually contributes to the onset and/or worsening AD manifestation or is merely a bystander epiphenomenon. This evidence concerns the gene MAPT and Alzheimer disease.