The analytical sensitivity 95% (95% CI 83–98%) and specificity 96% (95% CI 89–99%) for anti-N-protein IgG and the sensitivity of 90% (95% CI 76–96%) and specificity of 99% (95% CI 93–99%) for anti-N-protein IgA was previously determined on 208 Belgian patients with moderate to severe COVID-19 symptoms between days 14 to 18 after the onset of symptoms and 79 pre-COVID-19 pandemic serum representatives of various non-flavivirus and non-coronavirus infectious diseases [50]. The gene discussed is CD79A; the disease is infectious disease.