A study that analyzed the dynamics of Covid-19 in Brazil indicates that citizens infected with dengue may develop some immunity against the new coronavirus, in an investigation that has not yet been concluded.
In the professor’s view, the study points out that there is also the possibility that vaccines approved or under development for dengue may cause some type of protection against the new coronavirus
According to the study, released by the Brazilian press, researchers found that places that had many cases of dengue in 2019 and in the beginning of 2020 had fewer infections and deaths by Covid-19. The study was led by Brazilian scientist Miguel Nicolelis, professor at Duke University, in the United States, who, since the beginning of the pandemic, has been dedicated to studying the behavior of the new coronavirus in Brazil.
“Trying to look for an explanation, I found the Ministry of Health’s dengue map and, where it had taken a long time to reach Covid-19, like Mato Grosso do Sul, Mato Grosso and Paraná, it was where there were many cases of dengue, it was complementary. We found an inverse correlation. Places with a lot of dengue had fewer cases, fewer people died and the time to reach Covid-19 cases was longer, ”explained Nicolelis, quoted by the newspaper Estadão.
According to the researcher, it is possible that people who contracted dengue have developed a partial defense against the new coronavirus.
“I went to see other countries in the world. In 2020, according to data from January and February, it would be the biggest epidemic, but dengue fever started to disappear when the Covid-19 curve started to explode.
The two viruses are competing for the same susceptible population, but dengue needs a mosquito and Covid-19 is transmitted from person to person, much faster. In Africa, where there were many dengue cases, there were not many coronaviruses ”, analyzed Nicolelis. In the professor’s view, the study points out that there is also the possibility that vaccines approved or under development for dengue may cause some type of protection against the new coronavirus.
“We have a Japanese vaccine for dengue that is advanced, in phase three. If we prove that there is a protection of 30%, 40% or even 50%, we would have a vaccine for an emergency, to break the transmission of the virus ”, said the scientist. The study has not yet been published in a scientific journal, but it is available in the medRxiv research repository.
Dengue is a disease transmitted by the ‘Aedes aegypti’ mosquito, which needs standing water to proliferate, and can cause high fever, severe muscle pain, malaise, lack of appetite, headache, red spots on the body and can even lead to death. From January to August this year, 905,912 probable dengue cases were reported in Brazil and 433 deaths, according to data from the Ministry of Health.
In this period, the central-west region had the highest incidence of dengue, followed by the southern region. Both regions have the least cases of infection with the new coronavirus, which has been officially registered
in Brazil on February 26th. Brazil is the Portuguese-speaking country most affected by the pandemic and one of the hardest hit in the world, when counting the second number of deaths (more than 4.5 million cases and 138,108 deaths), after the United States.
Manaus may have achieved group immunity
The city of Manaus, heavily affected by the coronavirus pandemic, may have had so many infected people that its population now benefits from “group immunity”, according to a preliminary study. Published on the medRxiv website, the study analyzed infection data with mathematical modeling to estimate that 66% of the population had antibodies against the new coronavirus in Manaus, where the rate of contagion was rapid and brutal.
The percentage may be high enough to have crossed the threshold of group immunity, which happens when a sufficient number of elements in a population are immune to a disease, which is unable to spread more effectively, the authors of the study indicate, a group of 34 Brazilian and foreign researchers.
“The exceptionally high rate of infection suggests that group immunity played a significant role in the scale of the epidemic,” wrote the study authors, who are yet to undergo peer review. “Apparently, the exposure to the virus itself caused the drop in the number of cases and deaths in Manaus,” said the study’s coordinator, Ester Sabino, professor at the Faculty of Medicine of the University of São Paulo (FM-USP), to São Paulo State Research Support Foundation (Fapesp), which helped finance the work.
Manaus was a scene of chaos when the pandemic peaked in that city in May. But the death toll in the capital of 2.2 million has dropped dramatically in recent weeks, to an average of 3.6 a day, in the past 14 days. It is today one of the fastest reopening cities in the country. Brazil records the second highest number of deaths by Covid-19 in the world, over 139 thousand.
Health experts warn that trying to achieve group immunity is a dangerous path for policy making. “Group immunity through natural infection is not a strategy, it is a sign that a government has failed to control an outbreak and is paying for it with lost lives,” wrote Florian Krammer, professor of microbiology at Icahn School of Medicine at Mount Sinai Hospital in New York.
Other experts warn that immunity to the virus may be short-term. Manaus records 2,462 deaths caused by the new coronavirus. If it were a country, the city would have the second highest mortality rate in the world, with 100.7 deaths per 100,000 inhabitants.