PSMD1 and infection: On the other hand, since negative S1 and NP results for recomLine SARS-CoV-2 IgG were inclusion criteria for the naïve group, and antibody titers are known to decrease over time [9,10,11], while SARS-CoV-2-specific T cells can be observed in the absence of SARS-CoV-2-specific antibodies [12,13,14], an undetected past infection (without a history of PCR positivity) can never be totally excluded [38,39].