A new study that analyzed the coronavirus outbreak in Brazil has found a link between the spread of the virus and past outbreaks of dengue fever that suggests exposure to the mosquito-transmitted illness may provide some level of immunity against COVID-19.
The not yet published study led by Miguel Nicolelis, a professor at Duke University, and shared exclusively with Reuters, compared the geographic distribution of coronavirus cases with the spread of dengue in 2019 and 2020.
Surprisingly, in the study, coronavirus infection rates were found to be slower and lower in places that had suffered intense dengue outbreaks last year and early this year. It also found lower COVID-19 mortality rates in populations where the levels of antibodies to dengue were higher.
Nicolelis told Reuters the results are particularly interesting because previous studies have shown that people with dengue antibodies in their blood can test falsely positive for Covid-19 antibodies even if they have never been infected by the coronavirus.
“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 said, adding that further studies are needed to prove the connection.
This finding raises the possibility of the cross-reactivity between dengue’s Flavivirus serotypes and SARS-CoV-2, the study concluded. If this hypothesis is proven correct, that would mean dengue infection or immunisation with an efficacious and safe dengue vaccine could produce some level of immunological protection, the study further noted.
Nicolelis said his team came across the dengue discovery by accident, during a study focused on how Covid-19 had spread through Brazil, in which they found that highways played a major role in the distribution of cases across the country.
The states of Brazil that had the highest number of cases of dengue last year, Paraná, Santa Catarina, Rio Grande do Sul, Mato Grosso do Sul, and Minas Gerais, took much longer to reach a level of high community transmission compared to states with fewer dengue cases, Amapá, Maranhão, and Pará.
The coronavirus pandemic appears to be accelerating worldwide, with new cases soaring last week to a new seven-day high of almost two million, even as new deaths decreased, WHO statistics showed.
In a fresh global update, the World Health Organization said late Monday that during the week ending on September 20, 1,998,897 new cases of the novel coronavirus were registered around the world.
