Unexpected diagnosis of COVID-19-associated disorders by SARS-CoV-2-specific serology.

Facing the ongoing pandemic caused by SARS-CoV-2, there is an urgent need for serological assays identifying individuals with on-going infection as well as past coronavirus infectious disease 2019 (COVID-19). We herein evaluated the analytical performances of the CE IVD-labeled Abbott SARS-CoV-2 IgG assay (Des Plaines, IL, USA) carried out with the automated Abbott Architect™ i2000 platform at Hôpital Européen Georges Pompidou, Paris, France, using serum sample panels obtained from health-workers with COVID-19 history confirmed by positive nucleic acid amplification-based diagnosis and from patients randomly selected for whom serum samples were collected before the COVID-19 epidemic. The Abbott SARS-CoV-2 IgG assay showed sensitivity of 94 % and specificity of 100 %, demonstrating high analytical performances allowing convenient management of suspected on-going and past-infections. In addition, the SARS-CoV-2 IgG positivity rates were compared in COVID-19 positive and COVID-19 free areas from our hospital. Thus, the frequency of SARS-CoV-2-specific IgG was around 10-fold higher in COVID-19 areas than COVID-19 free areas (75 % versus 8%; P < 0.001). Interestingly, several inpatients hospitalized in COVID-19 free areas suffering from a wide range of unexplained clinical features including cardiac, vascular, renal, metabolic and infectious disorders, were unexpectedly found seropositive for SARS-CoV-2 IgG by systematic routine serology, suggesting possible causal involvement of SARS-CoV-2 infection. Taken together, these observations highlight the potential interest of SARS-CoV-2-specific serology in the context of COVID-19 epidemic, especially to assess past SARS-CoV-2 infection as well as possible unexpected COVID-19-associated disorders.