Dengue, transmitted by mosquitoes aedes aegyptiwas reintroduced in Brazil in the early 1980s.
I say reintroduced once the mosquito had been eliminated in Brazil in 1955 and in most of the Americas in the 60s. This happened after intense control campaigns initiated in Brazil with support from the Rockefeller Foundation.
Over the years, dengue has expanded geographically and epidemic outbreaks every two or three years have worsened in intensity. About 76% of dengue cases reported in Brazil since the year 2000 were observed from 2010 onwards.
This geographic expansion of dengue does not only happen in Brazil. Currently, about half of the world’s population in more than 125 countries lives at risk of dengue infection. This expansion has been driven by patterns of urbanization and globalization.
Climate change will further aggravate the situation if local adaptation measures are not adopted and global warming is not reduced.
Urban growth patterns in Brazil provide ideal conditions for aedes aegypti🇧🇷 According to data from Mapbiomas, from 1985 to 2021, urbanized areas tripled in Brazil, with even greater expansion of slums, especially in risk areas.
The lack of regular access to water forces the population to use containers, which are not always covered, which creates breeding grounds for mosquitoes. Areas without regular garbage collection also become important foci for the Aedes🇧🇷 Both are problems of lack of urban infrastructure.
This year Brazil is facing another dengue epidemic. There are already almost 1.4 million cases (until November) and 975 deaths. As there are no specific antivirals or treatments for dengue, measures are focused on mosquito control and educational campaigns. However, these measures have not been sufficient to contain the expansion of dengue.
The development of a dengue vaccine would change this scenario. Dengvaxia, from the pharmaceutical company Sanofi, was the first vaccine to be approved in several countries, including Brazil.
However, this vaccine carried a risk of serious adverse effects when administered to children who were not previously infected. In Brazil, this vaccine was used only in some municipalities of Paraná in 2016.
On the 8th, the Qdenga vaccine, developed by the pharmaceutical company Takeda, was approved for use in the European Union. In August this vaccine had already been approved for use in Indonesia. It is currently being evaluated for use in the United States and Brazil.
Qdenga is recommended for people aged four years and older, given as two doses three months apart. Clinical trials were done in eight countries, including Brazil. After four and a half years of follow-up, the vaccine prevented 84% of cases of hospitalization due to dengue and 61% of symptomatic cases.
The eventual approval of the vaccine for use in Brazil and its availability in the health system does not replace mosquito control measures, since chikungunya and zika are also transmitted by the Aedes🇧🇷 This year, more than 9,200 cases of zika have been reported, 42% in the state of Rio Grande do Norte, and about 170,000 cases of chikungunya, 31% in Ceará. There are no approved vaccines against chikungunya and Zika, but clinical trials are ongoing.
A future dengue vaccination campaign will have to be accompanied by educational actions so that the population does not abandon measures to prevent mosquito breeding sites.
Above all, the vaccine does not replace the need to improve urban infrastructure. Decent housing conditions are a human rights issue.
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