Inverse Correlation between Dengue Fever and COVID-19 spread in Latin America, the Caribbean and Asia

Here we investigated whether the dengue fever pandemic of 2019-2020 may
have influenced COVID-19 incidence and spread around the world. In Brazil,
the geographic distribution of dengue fever was highly complementary to
that of COVID-19. This was accompanied by an inverse correlation between
COVID-19 and dengue fever incidence that could not be explained by
socioeconomic factors. This inverse correlation was observed for 5,016
Brazilian municipalities reporting COVID-19 cases, 558 micro- and 137
meso-regions, 27 states and 5 regions. Brazilian states with high
population levels of dengue IgM in 2020 exhibited: (i) lower COVID-19 case
and death incidence, (ii) slower infection growth rates, and (iii) took
longer to accumulate COVID-19 cases. No such inverse correlations were
observed for the chikungunya virus, which is also transmitted by the Aedes
aegypti mosquito. The same inverse correlation between COVID-19 and dengue
fever incidence was observed for 145 locations (66 countries and the 64
states of Mexico and Colombia) in Latin America, the Caribbean, and Asia.
Countries with high dengue incidence took longer to accumulate COVID-19
cases than those without dengue. Although the dataset considered has
quality and availability limitations, these findings raise the possibility
of an immunological cross-reaction between dengue virus serotypes and
SARS-CoV-2, which could have led to partial immunological protection for
COVID-19 in dengue infected communities. However, further studies are
necessary to better test this hypothesis.