Exposure to Mosquito-Transmitted Dengue May Provide Immunity Against COVID-19

A study has found a link between the spread of the SARS-CoV-2 virus and previous outbreaks of dengue fever in Brazil, suggesting that exposure to the mosquito-transmitted illness could provide some immunity against COVID-19.

The study found a significant correlation between lower incidence, mortality and growth rate of COVID-19 among the Brazilian population that had higher levels of antibodies to dengue. In the study that has not yet been published by the Duke University (Durham, NC, USA) but shared exclusively with Reuters, researchers compared the geographic distribution of coronavirus cases with the spread of dengue in 2019 and 2020. They found that locations that had witnessed intense dengue outbreaks in 2020 or 2019 reported lower coronavirus infection rates and a slower increase in the number of COVID-19 cases. “This striking finding raises the intriguing possibility of an immunological cross-reactivity between dengue’s Flavivirus serotypes and SARS-CoV-2,” according to the study, referring to dengue virus antibodies and the novel coronavirus. “If proven correct, this hypothesis could mean that dengue infection or immunization with an efficacious and safe dengue vaccine could produce some level of immunological protection” against SARS-CoV-2, it added.

Miguel Nicolelis, a professor at Duke University who led the study, told Reuters that the results were especially interesting given that previous studies had shown that it was possible for people with dengue antibodies in their blood to test falsely positive for COVID-19 antibodies despite never being infected by the coronavirus. The researchers found a similar relationship between dengue outbreaks and a slower spread of COVID-19 in other parts of Latin America, as well as Asia and islands in the Pacific and Indian Oceans, according to Reuters.

“This indicates that there is an immunological interaction between two viruses that nobody could have expected, because the two viruses are from completely different families,” Nicolelis told Reuters, adding that further studies are needed to prove the connection.

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