Brazilian scientist leads promising dengue vaccine development at Butantan Institute

Neuza Frazatti has spent more than a decade chasing a problem that affects millions of Brazilians. As manager of the Viral Vaccine Pilot Laboratory at Instituto Butantan, she began her work on a dengue vaccine in 2010, long before the institute would announce preliminary results that the scientific community found genuinely promising. In December of last year, Butantan released data showing the vaccine achieved 79.6 percent efficacy in preventing dengue infection, based on a phase 3 clinical trial that followed more than 16,000 people over two years. The trial continues—volunteers are still being monitored—but the path forward is clear: once this final phase concludes, the institute will seek approval from Brazil's health regulator, Anvisa, and then move toward production and distribution.

The urgency behind this work becomes apparent when you consider what currently exists. Brazil has access to exactly one dengue vaccine, Dengvaxia, made by the French pharmaceutical company Sanofi Pasteur. But it comes with significant limitations. The vaccine is not recommended for people who have never been exposed to dengue virus before, a restriction based on the manufacturer's own studies and reinforced by warnings from both Anvisa and the World Health Organization. It is not part of Brazil's public immunization program, available only through private clinics. For a country where dengue is endemic and affects poor and working-class populations most severely, these constraints matter enormously.

Frazatti's vaccine addresses these constraints through its design. It is tetravalent—meaning it protects against all four types of dengue virus simultaneously. During the trial period, only types 1 and 2 circulated in Brazil, and the vaccine showed 89.5 percent efficacy against type 1 and 69.6 percent against type 2. But because it targets all four strains, people who receive it will be protected even against virus types they have never encountered. The vaccine comes as a single dose, remains stable in standard refrigerator temperatures, and requires no special storage infrastructure. These are not minor details. They are the difference between a vaccine that works in theory and one that can actually reach people living in difficult circumstances.

Frazatti's path to this moment began years earlier, in the early 2000s, when she introduced a new technology to Butantan with a different goal in mind: reducing the use of animals in vaccine research. She and her team established production of vaccines and viral antigens using Vero cells, a cell line derived from African green monkey kidney tissue. Previously, vaccines had been developed primarily in newborn mice. The first product made using this method was a novel rabies vaccine free of serum, approved by Anvisa in 2008, work that earned her the Péter Murányi Health Prize two years later. That innovation laid the groundwork for everything that followed.

Developing a dengue vaccine proved more complex than earlier work. "You have four types of virus, and the vaccine needs to be effective against all of them," Frazatti explained. To reach even the stage of developing the active pharmaceutical ingredient, her team conducted more than 200 experiments. The work required precision, patience, and the kind of sustained institutional commitment that is rare. She now leads teams ranging from 20 to 50 people depending on which phase of research is underway.

While the dengue vaccine moves toward regulatory approval, Frazatti's laboratory is also working on a trivalent covid-19 vaccine in its early stages. The team is developing the active ingredient for an immunization that would protect against three variants: the original Wuhan strain, the B.1 variant first identified in Manaus, and Omicron. She reflects on the pandemic as a moment when global scientific collaboration accelerated dramatically—researchers shared information in real time, allowing rapid characterization of the virus. But she also notes a critical vulnerability: the industry producing the raw materials and components needed for vaccine manufacturing was unprepared. That realization, she suggests, should prompt every country to develop pandemic response strategies.

Frazatti's vision for vaccine development is straightforward and uncompromising. "What I hope for is that we can have increasingly more production technologies that generate high-quality products, that induce a lasting response, and that are above all low-cost and easy to store, because the vaccine has to be for everyone," she said. Her dream, she added, is to develop a dengue vaccine that remains stable at even higher temperatures than current refrigeration, so that populations living in the most challenging conditions can access protection. That ambition—to make vaccines not just effective but genuinely universal—has guided her work from the beginning. In 2021, the international pharmaceutical association Parenteral Drug Association recognized her contributions to science with its Women in Life Sciences award. The dengue vaccine now awaits the final steps that could bring it to the people who need it most.