Prior dengue infection reduced virologically confirmed dengue risk (OR: 0.85, 95% CI: 0.75 to 0.98) and increased severe dengue risk (OR: 2.91, 95% CI: 1.23 to 6.87), with no significant impact on dengue hospitalization, dengue-related death, or all-cause mortality. These results challenge the view of prior infection as an independent risk factor.