SARS-CoV-2 Antigenemia as a Confounding Factor in Immunodiagnostic Assays: A Case Study
Konstantinos Belogiannis, Venetia A. Florou, Paraskevi C. Fragkou, Stefanos Ferous, Loukas Chatzis, Aikaterini Polyzou, Nefeli Lаgopati, Demetrios Vassilakos, Christos Kittas, Athanasios G. Tzioufas, Sotirios Tsiodras, George Sourvinos, Vassilis G. Gorgoulis
Abstract
Humoral immunity has emerged as a vital immune component against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Nevertheless, a subset of recovered Coronavirus Disease-2019 (COVID-19) paucisymptomatic/asymptomatic individuals do not generate an antibody response, constituting a paradox. We assumed that immunodiagnostic assays may operate under a competitive format within the context of antigenemia, potentially explaining this phenomenon. We present a case where persistent antigenemia/viremia was documented for at least 73 days post-symptom onset using 'in-house' methodology, and as it progressively declined, seroconversion took place late, around day 55, supporting our hypothesis. Thus, prolonged SARS-CoV-2 antigenemia/viremia could mask humoral responses, rendering, in certain cases, the phenomenon of 'non-responders' a misnomer.