Despite a daunting more than 130 million cases of SARS-CoV-2 infections to date worldwide, another global pathogen—the Aedes mosquito-borne dengue virus—saw a record number of over 400 million cases in 2019. But vaccine development has been challenging due to the need to protect equally against all four dengue strains. The discovery of new possible biomarkers to predict clinical and immune responses to dengue virus infection, published today in Nature Communications, could be critical to informing future vaccines.