High S-IgG seroprevalence in patients visiting emergency departments in North Rhine-Westphalia, Germany
To determine SARS-CoV-2 humoral immunity, we first measured seroprevalence and levels of S-IgG in all participants. S-IgG could be detected in 95.6% of the participants. Of the 4.4% S-IgG-negative participants, 27.9% reported drug immunosuppression at the time of sampling. Of those reporting no drug immunosuppression, 31.8%, 29.5%, 6.8%, 22.7%, 6.8%, and 2.3% reported 0, 1, 2, 3, 4, or >4 previous S-antigen contacts, respectively (Fig. 