CXCL9 and CXCL10 as well as high IgG levels were found to be biomarkers of severe CHIKV symptoms. Previously, CXCL10 has been associated with severe viral disease supporting a role for CXCL10 in severe CHIKV disease [34] [35] [36] [37] . These studies did not find an association with CXCL9 and severity as seen in our CHIKV patients. Our findings suggest high CXCL10 and CXCL9 associated with severity to be a unique signature of CHIKV. Interestingly, not only are CXCL10 and CXCL9 expressed in RA and other arthritis related disease patients [38] [39] [40] [41] , but they have been shown to be biomarkers for RA symptoms, implying a similar mechanism for joint destruction in CHIKV disease [42] . Moreover, CXCL9 and CXCL10 may be contributors of persistent immune activation in CHIKV disease leading to chronic symptoms, which implies cytokine immunomodulation may significantly improve patient treatment and recovery. Importantly, CXCL10 also has prognostic value in the treatment of viral hepatitis where CXCL10 levels follow disease recovery [43] supporting our finding and proposes a prognostic role for CXCL10 in CHIKV. Furthermore, our data puts forth CXCL10 and CXCL9 as possible drug targets for treatment of CHIKV symptoms in the convalescence phase due to the association with severity; however, further investigation is needed on CXCL10 and CXCL9 efficacy. In addition, not only are the identified cytokines useful as possible drug targets but the cytokine signatures described can also be applied when testing newly developed CHIKV therapeutics. As CHIKV therapeutics are evaluated in the CHIKV disease model, cytokine profiles can be used as an output for determining the efficacy of the novel therapeutics.