Figure 1.

Dynamics of (A) anti–SARS-CoV-2 IgG in serum and (B) SARS-CoV-2 viral load in upper airways. IgG measured by N-protein–based ELISA³ (NovaLisa, NovaTec; validated in-house; approved by the Federal Agency for Drugs and Health Products). A level > 11 NTU (“NovaTec units”) is interpreted as positive, and 9-11 NTU, as borderline. Viral load measured by a laboratory-developed semi-quantitative real-time reverse transcriptase–polymerase chain reaction (RT-PCR) targeting the N (nucleocapsid) and RdRp (RNase-dependent RNA polymerase) genes. A phocine distemper virus was used as a control to test for extraction errors or presence of inhibitors. A cycle threshold value < 40 is interpreted as positive.