Frequency of auto-Abs against type I IFNs in the WNVIC, WNVF, and WNVD groups and the two WNVD subgroups (WNVD without evidence of neuroinvasive disease and WNND) relative to the general population in the seven new cohorts and the overall study population consisting of all 13 cohorts. Horizontal bars represent the 95% CI limits. IFN-α, auto-Abs neutralizing IFN-α2 (regardless of effects on other IFNs); IFN-ω, auto-Abs neutralizing IFN-ω; IFN-α ± ω ± β, auto-Abs neutralizing IFN-α2 and/or IFN-ω and/or IFN-β; IFN-α + ω, auto-Abs neutralizing both IFN-α2 and IFN-ω; WNND, WNV neuroinvasive disease. ns, nonsignificant; ****P < 10⁻⁴.