SARS-CoV-2 antigenemia/viremia masks seroconversion in a COVID-19 patient

Immune responses against SARS-CoV-2 have been vigorously analyzed. It has been proposed that a subset of mild or asymptomatic cases with undetectable antibodies may clear the virus in a T-cell cytotoxic-dependent manner, albeit recent data revealed the importance of B-cells in that regard. We hypothesized that underdiagnosed antigenemia/viremia may conceal humoral response possibly through immunocomplex formation. We report the first case of late-onset seroconversion detected following decline in antigenemia/viremia levels. Consequently, classification of at least a subset of COVID-19 cases as non-responders might not represent a true immunobiological phenomenon, rather reflect antibody masking due to prolonged antigenemia/viremia.