In our study, HLA-A*33:01 conferred protection against severe dengue, as shown by the decreased frequency of this allele in patients which developed severe dengue (DHF/DSS) compared to the background population (OR = 0.2, Pc = 0.0022) as well as in patients who developed shock compared to the background population (OR = 0.6, Pc = 0.0044). Here, HLA-A is linked to Dengue hemorrhagic fever.