IFNG and infection: However, a study in school children shows that pre-existing tumour necrosis factor (TNF)-α, interferon (IFN)-γ, and interleukin (IL)−2-producing DENV-specific T-cells are protective towards development of a subsequent symptomatic secondary infection, suggesting that the impact of cross-reactive T-cells in dengue is complex and the extent of occurrence of OAS in SD remains poorly understood19.