It is possible that prior exposure to DENV could provide some degree of cross-protection to SARS-CoV-2 infection, rendering it less severe in regions where dengue is endemic, as supported by a report from Singapore where a man and a woman (both aged 57 years) were originally COVID-19 virus-positive and false-positive in serological tests for dengue, including DENV-IgM and IgG [68]. This evidence concerns the gene CD40LG and dengue disease.