COVID-19 Virus Infection and Transmission are Observably Less in Highly Dengue-Endemic Countries: Is Pre-Exposure to Dengue Virus Protective Against COVID-19 Severity and Mortality? Will the Reverse Scenario Be True?

Abstract

Global severity maps of ongoing dengue epidemic and COVID-19 pandemic do not tend to overlap. Countries with high dengue endemicity (>1.5 million cases/year) are observably less hit by COVID-19 in terms of infection, transmission and mortality. Based on non-overlap of dengue and COVID-19 severity maps in general and increasing evidences of SARS-CoV-2 false-positivity in dengue antibody tests, we wonder whether regular pre-exposure to dengue virus (DENV) in highly dengue endemic countries is providing some extent of protection against COVID-19 severity. We also wondered whether immunization of susceptible populations in dengue non-endemic countries (e.g. Europe and North America) with available live-attenuated dengue vaccines, will cue the anti-viral immune response to thwart COVID-19. Risk of developing post-vaccination antibody-dependent enhancement (ADE) is low as dengue is not endemic in the aforesaid regions. Understanding the consequences of dengue and COVID-19 co-endemicity in the upcoming days is another area of huge concern. Although, it appears that dengue-induced immunity is ‘thwarting’ COVID-19, it is not clear whether conversely, COVID-19 convalescent individuals will also be resistant to future dengue attacks. On the contrary, such individuals may show higher susceptibility to DENV due to ADE caused by cross-reactive COVID-19 antibodies. The latter may bind to DENV without neutralizing the virus; instead, such antibodies may facilitate cellular entry of DENV by means of their Fcregions attached to the susceptible cells. This possibility also cautions against complications that may arise on implementing SARS-CoV-2 vaccinations in highly dengue endemic countries.