SIRPA and COVID-19: Considering the crucial role of myeloid cells in provoking hyperinflammatory responses associated with coronavirus disease 2019, a camelid-derived single-domain antibody specifically recognizing human signal-regulatory protein-α (SIRPα) as a biomarker for myeloid cells has been generated and radiolabeled with 64Cu, that is, [64Cu]copper-SIRPα-nanobody ([64Cu]Cu-SIRPα-Nb), for in vivo PET imaging.