The ISAVRAD U19 proposes a five-site, two-arm (patients and controls), longitudinal (3 assessments/subject) study enrolling 4,300 individuals. All 5 enrollment sites are experienced in recruiting genetically homogenous cohorts. Pilot data of various types are provided in the respective projects and cores. Participants will be men and women (~50:50 ratio) who are > 60 years of age and either have a history of polymerase chain reaction (PCR) test positive COVID-19 infection (75% of sample) or have no history of COVID-19 (25% of sample). Evaluations will be performed upon enrollment, 18 months, and 36 months. Evaluations will comprise a standardized data acquisition battery including assessment of clinical status and serum sampling for fluid-based biomarkers and genetics. Neuroimaging will be conducted at enrollment and at 18 months. Data acquisition, preprocessing, archiving and sharing – both within the U19 and with the scientific community at large – will be overseen by the Administrative, Clinical, Neuroimaging, and Data Management & Statistics Cores of the U19. The Neuroimaging Core will manage neuroimaging acquisition (2 assessments/subject), quality control, harmonization, data archiving and data sharing at all five study sites. Image acquisition, quality control and harmonization strategies will emulate those of ADNI3 and Mark VCID supplemented by team expertise. Minimal data preprocessing will use pipelined approaches both volumetric and surface-based. Surface-based analyses will emulate Enhancing Neuro Imaging Genetics through Meta-Analysis (ENIGMA) protocols, with the expectation that other large studies of the post-acute sequelae of COVID-19 (PASC) will emerge and that ENIGMA community will embrace the challenge of ongoing data exploration both meta-analytic and mega- analytic. Aim 1: Image Acquisition, Harmonization and Quality Control. Structural MRI and functional MRI images will be acquired at all five study sites. Structural MRI acquisitions will emulate those of ADNI3, UKBioBank, Lifespan HCP, MarkVCID and GOBS. Functional MRI acquisitions will emulate the latest GOBS. The Neuroimaging Core will coordinate acquisition across sites, including harmonization and quality control. Aim 2: Image Preprocessing and Pipeline analytics. The Neuroimaging Core will perform post-acquisition quality control, image preprocessing (artifact removal, motion correction, etc.), and run widely used volumetric and surface-based pipeline analyses. Blood-oxygen-level-dependent (BOLD)-based indices of neuronal dysfunction will be cross validated with glucose metabolism and blood flow. Aim 3: Image Archiving, Access Control, and Sharing. Anonymized raw and processed volumetric and surfaced- based images and image-derived data (region of interest [ROI] values) and visual-inspection scores will be archived in the XNAT system. Spreadsheet-compatible data will be provided to the Data Management and Statistics Core.