DENV‐specific cells targeting DENV 1–4 NS1 protein in acute DENV, ZIKV, and DENV/ZIKV‐patients, and donors experiencing dengue. Peripheral blood mononuclear cells (2 × 105 in 0.1 mL) were incubated with recombinant mammalian (rm) NS1 (0.1 μg/mL) derived from four different DENV serotypes or PHA for 20 h and IFNγ production was measured by ELISPOT assay. (a) Representative IFNγ production from one representative exposed donor, DENV, ZIKV, and DENV/ZIKV‐patients are shown against rmNS1. (b) The values obtained of IFNγ production, expressed as spot‐forming cells (SFC) relative to 106 PBMC, is shown for the rmNS1 and PHA were compared between them and with those in exposed healthy controls. Graphs show the median, 25th and 75th percentile from acute‐patients and DENV‐exposed ZIKV naïve donors. Statistical significance was determined by using the two‐tailed Mann–Whitney test, where p < 0.05 were considered significant (*p < 0.05; **p < 0.01).