Those who survive it often say they never want to experience it again.
As Brazil enters its hot, wet summer season, infectious disease specialists are confronting a dual epidemic: the dengue virus itself and the misinformation that prevents people from accepting the vaccine developed to stop it. Despite broad public confidence in the vaccine's efficacy, false claims circulating on social media have delayed or deterred vaccination for nearly a third of those surveyed. The struggle unfolding in Brazil reflects a universal tension of our era — that the tools to prevent suffering exist, yet the information environment shapes whether people will reach for them.
- Dengue cases are climbing as Brazil heads into summer, and specialists warn the coming months could bring deaths, hospitalizations, and widespread economic disruption from a disease that has resisted control since the 1980s.
- A survey of 2,000 Brazilians reveals a troubling paradox: 88% believe the vaccine works, yet 41% have encountered misinformation online, and nearly 30% delayed or discouraged vaccination because of safety doubts spread through social media.
- The most vulnerable to misinformation are a core group of skeptics — predominantly older, male, and lower-income — many of whom have had contact with dengue yet still underestimate how serious the disease is.
- Vaccines have become entangled in political identity since the COVID-19 pandemic, and experts say depoliticizing the conversation is now as urgent as expanding access to remote regions and underserved communities.
- Health authorities are responding with professional training for communicators, a national awareness campaign launching on Brazil's Dengue Control Day, and the reminder that the vaccine took 15 years to develop — directly countering claims it was rushed.
Brazil is entering summer with dengue cases on the rise and infectious disease specialists alarmed — not only by the virus, but by the false information online that is keeping people from getting vaccinated. Alberto Chebabo, president of the Brazilian Society of Infectology, describes the coming surge as deeply concerning and is calling on government and pharmaceutical companies to dramatically expand vaccination programs across more age groups and cities. Dengue, he stresses, is not a minor illness: it kills, hospitalizes, and leaves survivors determined never to experience it again.
A study commissioned by Takeda and conducted by Ipsos, in collaboration with Brazil's infectious disease and immunization societies, surveyed 2,000 people and found a striking paradox. Eighty-eight percent believe the dengue vaccine is effective, yet 41% have encountered misinformation on social media, and nearly 30% delayed their own vaccination or discouraged others because of doubts about safety and efficacy. Another 10% decided not to vaccinate at all based on online claims or word-of-mouth. The most common false narratives involve the vaccine's effectiveness, the severity of dengue, supposed miracle cures, and misinformation about transmission.
The study identified a core group of skeptics — about 10% of respondents, mostly over 55, slightly more male than female, and concentrated in lower-income brackets — who are especially susceptible to misinformation. Notably, 27% of this group either don't believe dengue is serious or don't know, despite 77% having had contact with the disease.
Renato Kfouri, vice president of the Brazilian Society of Immunizations, argues that health professionals need better training to reach hesitant people, addressing the five barriers the WHO identifies: confidence, complacency, convenience, communication, and context. Chebabo adds that the politicization of vaccines — a problem that deepened during the COVID-19 pandemic — must be dismantled, since dengue spares no one regardless of political affiliation.
Brazil made history in December 2023 as the first country to integrate a dengue vaccine into its national immunization program. The vaccine took 15 years to develop, directly refuting claims it was rushed. As summer approaches, authorities are launching the campaign 'Without a Shadow of Dengue. It Depends on You,' with projections planned for major cities on November 23, Brazil's National Dengue Control Day. The central question is whether expanded access and better communication can outpace the misinformation standing between millions of Brazilians and protection.
Brazil is heading into summer with a problem that has nothing to do with the weather. Dengue cases are climbing as the season approaches, and the country's infectious disease specialists are sounding an alarm not just about the virus itself, but about something harder to fight: the false information spreading online that keeps people from getting vaccinated.
Alberto Chebabo, president of the Brazilian Society of Infectology, put it plainly. The coming months will be hot and wet—ideal conditions for dengue to spread. The disease has been fought since the 1980s with limited success, and this year's surge is "deeply concerning." But what worries Chebabo most is not just the virus. It's that people are refusing protection because they've read something untrue on their phones. He wants the government and pharmaceutical companies to dramatically expand vaccination programs, reaching far more of the population across more age groups and more cities. Dengue, he emphasized, is not a simple illness. It kills. It hospitalizes. It keeps people from work. Those who survive it often say they never want to experience it again.
A new study commissioned by the pharmaceutical company Takeda and conducted by the research firm Ipsos, in collaboration with Brazil's infectious disease and immunization societies, surveyed 2,000 people to understand how misinformation shapes vaccination decisions. The findings reveal a paradox. Eighty-eight percent of respondents believe the dengue vaccine is an effective prevention tool. Most rated it as very important to have available in the public health system. Yet despite this confidence, false information is actively undermining vaccination efforts. Forty-one percent of those surveyed reported encountering vaccine misinformation on social media. Nearly 30 percent said they had either delayed their own vaccination or discouraged others from getting vaccinated because of doubts about safety and efficacy. Another 10 percent decided not to vaccinate at all based on information from online sources or word-of-mouth. Even among those who didn't change their minds, 17 percent were left uncertain by what they'd read.
The most common false claims circulating involve the vaccine's effectiveness, the severity of dengue itself, supposed miracle cures, and incorrect information about how the disease spreads. The study identified a core group of vaccine skeptics—about 10 percent of respondents—who are especially vulnerable to misinformation. More than half of them are over 55 years old, slightly more men than women, and concentrated in lower-income brackets. Notably, 27 percent of this group either don't think dengue is serious or don't know whether it is, despite 77 percent having had contact with the disease.
Renato Kfouri, vice president of the Brazilian Society of Immunizations and head of the immunization department at the Brazilian Society of Pediatrics, argues that health professionals need better training to communicate with vaccine-hesitant people. The World Health Organization has identified five barriers to vaccination uptake—confidence in vaccines and public health strategy, complacency about disease risk, convenience of access, communication, and context. Each requires a different approach. Building confidence means showing people the real dangers of dengue. Ensuring convenience means making vaccines available everywhere, including remote regions. Communication falls to journalists and health workers. Context sometimes requires tailored strategies for specific communities, whether shaped by geography, religion, or politics.
One barrier stands out as particularly damaging: the politicization of vaccines. Chebabo stressed that dengue affects everyone equally, regardless of political affiliation, religious belief, or sports team loyalty. Yet vaccines have become entangled in political discourse, a problem that intensified during the COVID-19 pandemic and spilled over into confidence in all vaccination programs. Removing vaccines from political argument, he said, is essential to rebuilding trust.
On a positive note, 91 percent of survey respondents pay attention to vaccination campaigns, 90 percent believe vaccines in general bring benefits, and 95 percent say they verify vaccine information. When people encounter positive messages about vaccines on social media, 77 percent report feeling confidence, calm, or optimism. Television remains the primary source of vaccine information at 59 percent, followed by social media at 49 percent and health clinics at 47 percent.
Brazil made history on December 21, 2023, when it became the first country to integrate a dengue vaccine into its national immunization program. Vivian Lee, medical director of Takeda, noted that the vaccine took 15 years to develop—a fact that directly contradicts the false claim that it was rushed. As summer approaches and cases rise, health authorities are launching a campaign called "Without a Shadow of Dengue. It Depends on You," with projections planned for Rio de Janeiro, São Paulo, Brasília, and Salvador on November 23, Brazil's National Dengue Control Day. The question now is whether better communication and expanded access can overcome the misinformation that stands between millions of Brazilians and protection.
Citações Notáveis
This is a disease that brings considerable harm to society, not only in terms of deaths but in terms of absenteeism, suffering, hospitalization. It is not a simple disease.— Alberto Chebabo, president of the Brazilian Society of Infectology
We need to remove the vaccine from political discourse. The disease affects everyone the same way, regardless of political conviction, religious belief, or sports team loyalty.— Alberto Chebabo
A Conversa do Hearth Outra perspectiva sobre a história
Why does misinformation spread so much faster than the vaccine itself?
Because it doesn't require a clinic visit or a needle. It just requires someone to feel afraid or uncertain, and then to share that feeling with others who already doubt institutions.
But the study shows 88 percent believe the vaccine works. So what's the gap?
Belief and action are different things. You can believe something is good and still hesitate when you see conflicting stories online, especially if you're already skeptical about authority.
The study mentions that 27 percent of vaccine skeptics don't think dengue is serious. How do you convince someone of a threat they don't see?
You have to meet them where they are. If they've never had severe dengue, or if they know someone who had it mildly, the disease feels abstract. The vaccine feels like a solution to a problem they don't believe exists.
Chebabo said dengue has been fought since the 1980s with few victories. Why has it been so hard to control?
Because it's spread by mosquitoes that breed in standing water in cities—in flower pots, gutters, anywhere it rains. You can't vaccinate a mosquito. You need both vaccination and environmental control, and that requires coordination across neighborhoods, cities, regions. It's messy.
What does it mean that the vaccine became political?
It means people stopped asking "Is this safe?" and started asking "Who is telling me to take this?" If your political opponents are pushing vaccines, you resist, even if the science is sound. COVID poisoned the well for all vaccines.
So what actually changes people's minds?
Trust. A doctor they know. A neighbor who got vaccinated and didn't get sick. Information that comes from someone they already believe in, not from a government or a company.