A new study analyzing the coronavirus outbreak in Brazil found a link between the spread of the virus and previous dengue outbreaks, suggesting that exposure to the mosquito-borne disease may induce some level of immunity to COVID -19 offers.
The as-yet-unpublished study by Miguel Nicolelis, a professor at Duke University, shared with Reuters news agency, compared the geographic distribution of coronavirus cases with the spread of dengue in 2019 and 2020.
Locations with lower coronavirus infection rates and slower case growth were places where intense dengue outbreaks had occurred this year or last, Nicolelis noted.
“This remarkable finding opens up the fascinating possibility of immunological cross-reactivity between dengue flavivirus serotypes and SARS-CoV-2,” says the study with reference to dengue virus antibodies and the novel coronavirus.
“If this hypothesis proves correct, it could mean that dengue infection or immunization with an effective and safe dengue vaccine can provide some level of immunological protection against the coronavirus,” she added.
Nicolelis told Reuters the results were particularly interesting because previous studies have shown that people with dengue antibodies in their blood can falsely test positive for COVID-19 antibodies even if they have never been infected with the coronavirus.
“This suggests that there is an immunological interaction between two viruses that nobody could have expected because the two viruses come from completely different families,” Nicolelis said, adding that more studies are needed to prove the link .
The study was published on the MedRxiv preprint server before the peer review and will be submitted to a scientific journal.
It shows a significant correlation between lower incidence, mortality and growth rate of COVID-19 in populations in Brazil where dengue antibodies were higher.
Brazil has the third highest total number of COVID-19 infections worldwide with more than 4.4 million cases – only behind the US and India.
In states like Paraná, Santa Catarina, Rio Grande do Sul, Mato Grosso do Sul, and Minas Gerais, with high incidence of dengue last year and earlier this year, it took much longer for COVID-19 to reach high levels of community transmission to states like Amapá, Maranhão and Pará, who had fewer dengue cases.
The team found a similar relationship between dengue outbreaks and a slower spread of COVID-19 in other parts of Latin America, as well as in Asia and the islands in the Pacific and Indian Oceans.
Nicolelis said his team came across the dengue discovery by chance while conducting a study of the spread of COVID-19 in Brazil, which found that highways play an important role in the distribution of cases across the country.
After the team identified certain non-case-sensitive points on the map, they looked for possible explanations. A breakthrough came when the team compared the spread of dengue fever to that of the coronavirus.
“It was a shock. It was a total accident,” said Nicolelis. “In science, you shoot something and hit a target that you never thought you would hit.”