Brazilian study suggests dengue antibodies could offer protection against COVID-19
A new study has found a link between past exposure to dengue and immunity against COVID-19. The study, conducted in Brazil, observed that regions where people had contracted dengue in the previous year witnessed fewer coronavirus infections, infection growth rates, and deaths. Notably, existing studies have shown that COVID-19 patients can test positive for dengue antibodies. Here are more details.
The study, which is yet to be peer-reviewed, was led by Miguel Nicolelis, a professor at Duke University. The researchers used mathematical modeling and compared the geographic distribution of coronavirus cases with the spread of dengue in 2019 and 2020. Brazil is the world's third worst-affected country with 45,60,083 COVID-19 cases and 1.37 lakh deaths as of Tuesday.
The study stated, "We discovered that the geographic distribution of dengue fever, amounting to more than 3.5 million cases from January 2019-July 2020, was highly complementary to that of COVID-19." "States where a large portion of the population had contracted dengue reported lower COVID-19 cases and deaths, and took longer to reach exponential community transmission, due to slower SARS-CoV-2 infection growth rates."
The study noted significant negative correlations between COVID-19's incidence, infection growth rate, and mortality to the percentage of people with dengue antibodies. This inverse correlation between COVID-19 and dengue fever was also observed in Asia, Latin America, and islands in the Pacific and Indian Oceans. No such correlations were observed for the chikungunya virus, transmitted by the same mosquito vector.
"This striking finding raises the intriguing possibility of immunological cross-reactivity between dengue's Flavivirus serotypes and SARS-CoV-2," the study said. "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 for SARS-CoV-2 before a vaccine for SARS-CoV-2 becomes available," it added.
Speaking to Reuters, Nicolelis said the results are interesting since previous studies have shown that people with dengue antibodies can falsely test positive for COVID-19 antibodies, despite never having been infected by the coronavirus. A team of researchers from CSIR's Indian Institute of Chemical Biology—led by Subhajit Biswas—had earlier suggested that dengue antibodies can bind with SARS-CoV-2. This study is yet to be peer-reviewed.
In another study, yet to be peer-reviewed, they had claimed that dengue antibodies can sometimes give a false positive when tested for SARS-CoV-2 antibodies. An Israeli study, published in the peer-reviewed Clinical Infectious Diseases journal last month, stated that COVID-19 patients can test positive for dengue antibodies and vice-versa. Nicolelis told Reuters further studies are needed to prove the connection between the two diseases.
