Specificity was assessed with samples from 500 healthy German blood donors (HBD) and 40 patients each with West Nile virus (WNV) or Zika virus (ZIKV) infection.<h4>Results</h4>Sensitivities were 90.5%/70.0%/0% (t1/t2/t3) for NS1, 33.3%/85.0%/77.3% for IgM, 66.7%/100%/100% for IgG, and 33.3%/65.0%/100% vs. 19.1%/50.0%/100% for IgG 2.0 (standard vs. alternative cut-off). The gene discussed is CD40LG; the disease is infection.