Long COVID brain fog and muscle pain are associated with longer time to clearance of SARS-CoV-2 RNA from the upper respiratory tract during acute infection Annukka A. R. AntarTong YuZoe O. DemkoChen HuJeffrey A. TornheimPaul W. BlairDavid ThomasYukari C. ManabeOutSMART Study Group Frontiers in Immunology April 2023 DOI PDF URL