08/14/2026 | Isabella Tardelli Maio/Giovanna Vitor | Le Monde Diplomatique Brasil

https://diplomatique.org.br/movimento-antivacina-politica-desinformacao-e-desafios-a-saude-publica/ 

The narratives used to justify refusing vaccination are diverse, and the decline in vaccination coverage has raised concerns among public officials, health professionals, and society at large. What factors contribute to the strengthening of the anti-vaccine movement, considering its historical trajectory, contemporary methods of dissemination, and its impact on public perception regarding vaccination?

Introduction

According to research conducted by the Laboratory for the Study of Information Disorder and Public Policy (DesinfoPop/FGV, 2025), Brazil accounts for 40% of all anti-vaccine content circulating in Latin America and the Caribbean. This figure is particularly significant given the observed drop in vaccination coverage in recent years and prompts reflection on the factors contributing to rising vaccine hesitancy and the spread of vaccine-related disinformation. The survey indicates that, over the last decade, the country has been responsible for the circulation of more than 580,000 pieces of anti-vaccine content within online communities.

The narratives used to justify refusing vaccination vary widely. The study identified claims linking vaccines to alleged risks such as "sudden death," "poisoning," "autism," and even alterations to human DNA. Generally, this content relies on information taken out of context, misinterpretations of rare adverse events, or claims lacking scientific backing. Despite this, such content reaches a substantial audience and contributes to shaping negative perceptions regarding immunization. The mapping conducted by the researchers analyzed over 81 million messages published between 2016 and 2025 across 1,785 digital communities spanning dozens of countries[1].

Although vaccine resistance is not a new phenomenon, the expansion of digital social networks and the growing circulation of misinformation have given the problem a new dimension. In Brazil, this process took on specific characteristics during and after the COVID-19 pandemic, as scientific debates became heavily intertwined with political and ideological disputes. In this context, understanding the rise of the anti-vaccine movement and its impact on vaccination coverage is crucial for formulating health communication strategies and strengthening public immunization policies.

International context: the origin and reconfiguration of anti-vaccine movements

Since ancient times, various techniques have been developed to combat diseases and reduce their impact on populations. However, immunization via vaccination is a relatively recent practice in human history. Broadly speaking, vaccination involves introducing an antigen into the body to stimulate the immune system to produce defenses against a specific infectious agent. In the case of smallpox—one of the deadliest and most contagious diseases ever recorded—it was observed that individuals who survived the infection acquired protection against future exposure. Based on this observation, practices emerged that sought to artificially induce this immunity[2].

One of the earliest forms of immunization was variolation, developed in China around the 10th century. The method involved using material taken from the lesions of infected individuals—usually ground into a powder—to induce a milder form of the disease and, consequently, generate future protection. Although risky by modern standards, the technique represented a significant advance in the fight against the disease[3].

Eight centuries later, the research of British physician Edward Jenner paved the way for the development of the first modern vaccines. Upon observing that rural workers who had contracted cowpox appeared to be protected against human smallpox, Jenner hypothesized that exposure to the bovine disease might confer immunity. To test this, in 1796, he inoculated an eight-year-old boy with material from cowpox lesions. The boy developed only mild symptoms and, after recovering, was exposed to the human smallpox virus. As he did not contract the disease, Jenner concluded that the prior cowpox infection had conferred protection against the more severe form of the illness, thereby laying the foundations for modern vaccination[4]. It is important to note that this experiment took place in a historical context that predated the ethical and scientific protocols currently governing research involving human subjects. 

Today, vaccine development undergoes rigorous preclinical and clinical research stages, as well as evaluation by ethics committees and regulatory agencies, prior to any administration to the general population.

A study published in 2024 indicated that, since 1974, vaccination has averted approximately 154 million deaths worldwide, including 146 million deaths among children under the age of five—101 million of whom were infants under one year old [5]. Nevertheless, there has been a rise in groups resistant to vaccination, driven by religious, cultural, political, and health-related factors. Although vaccine hesitancy is not a recent phenomenon, a significant milestone in the contemporary anti-vaccine movement occurred in 1998, when British physician Andrew Wakefield published a study in the scientific journal *The Lancet* suggesting a link between the MMR vaccine (measles, mumps, and rubella) and the development of autism in children [6].

Subsequent investigations revealed that the results had been manipulated and that there was no scientific evidence to support such a link. Consequently, the article was retracted by the journal, and Wakefield lost his medical license [7]. Despite the study's broad scientific refutation, its impact helped strengthen anti-vaccine rhetoric in various countries, fueling doubts about vaccine safety and fostering the spread of misinformation that persists today, particularly in digital spaces.

While the anti-vaccine movement—also known as "antivax"—has gained greater visibility in recent decades due to globalization and the expansion of media, its origins predate the contemporary era by a wide margin. The first organized expressions of opposition to vaccination emerged as early as the 19th century, in response to mandatory immunization policies implemented by certain governments. In England, smallpox vaccination became mandatory for the first time in 1853 under the Vaccination Act, which required the immunization of children during their first months of life. However, the measure's implementation faced strong resistance from segments of the population who questioned both the efficacy and safety of the vaccines and the legitimacy of state intervention in individual decisions. Difficulties in enforcing the policy led to successive relaxations of the legislation, culminating in the creation of a "conscientious objection" clause in 1898 and the expansion of exemption grounds in 1907[8] [9].

Against this backdrop, organizations dedicated to opposing mandatory vaccination emerged. Notable among them was the London Society for the Abolition of Compulsory Vaccination, founded in 1880 and later renamed the National Anti-Vaccination League. The group grew to include over 100 branches and approximately 10,000 members, becoming one of the first formally structured organizations to oppose immunization policies[10].

A brief history of vaccination and vaccine resistance in Brazil

Although the topic is currently in the spotlight, vaccine resistance is an issue that researchers and health professionals have been familiar with for decades—and our first challenge involved smallpox. In 1804, a figure from Imperial Brazil emerged as a key player in the introduction of vaccines to the country: the Marquis of Barbacena. A military officer, diplomat, and politician, the Marquis of Barbacena (1772–1842) coordinated with the monarchy to transport enslaved people who had already been immunized—a practice once known as "arm-to-arm transport." Immunization was achieved through a chain of transmission: the animal virus was intentionally administered to one person, and the material was subsequently extracted and used on another healthy individual. Initially, immunization efforts were focused solely on the Royal Court. It was not until 1837 that the vaccine became mandatory for children, and in 1846, for adults.

However, this mandate did not yield effective results; it was against this backdrop that the Vaccine Revolt emerged in 1904. The uprising was a reaction to the stance taken by public health official Oswaldo Cruz—a position reinforced by legislation passed by the National Congress on October 31, 1904, which empowered the police to force entry into homes so that health agents could administer the vaccine. Despite the authorities' concern with combating the smallpox epidemic, the population did not respond positively to the measures, and a fierce popular rebellion broke out on November 13 of that same year.

Declining vaccination coverage in Brazil: a contemporary issue

The National Immunization Program (PNI) was established in the 1970s—a public policy that played a crucial role in expanding the entire vaccination system. During that same period, vaccination campaigns against measles and meningococcal meningitis were carried out. The years spanning the 1970s through the early 2000s marked the "golden age" of vaccination coverage. According to data from the National Immunization Program Evaluation Information System (SIAPI), the campaign against polio achieved 100.7% coverage during its first phase in 2002, while seasonal influenza vaccination among the elderly reached 99.9% coverage. See the table below:

However, starting in 2016, a sharp decline in coverage began, particularly regarding childhood immunization: the coverage rate for the MMR vaccine, for instance—which reached 96% of children in 2015—dropped to 84% in 2017, thereby opening the door to new windows of infection in the country.

What was once spread merely by word of mouth among vaccine-resistant circles found a space to call its own in the era of digital networks. Beyond simply expanding their reach, extremists were able to access new horizons and "arguments"—however wildly unfounded, such as the aforementioned link between vaccines and autism—to justify their actions. Bringing this into the context of the pandemic, between 2020 and 2023, Brazil experienced a renewed uprising, featuring new and far-reaching networks for the dissemination of ideas—but now with the backing of high-ranking executive officials, starting with the president at the time, Jair Messias Bolsonaro, who came to be viewed as the movement’s "ringleader":

“Why force a ‘child’ to get vaccinated? What are the odds of a child, for instance, contracting the virus and dying? […] It looks like—I don’t want to state it as fact—but it looks like the vaccine lobby. […] The interests of pharmaceutical companies making billions off the vaccine. Could that be it? It makes no sense. From what I see in studies—I’m mentioning this here—studies regarding those who have already contracted the virus and recovered, obviously... [For these people] the vaccine is useless, yet the pressure continues.”

– Excerpt from a press conference on October 14, 2021

In another instance, on December 17, 2020, the former president remarked sarcastically:
“If you turn into an alligator, that’s ‘your’ problem. If you turn into Superman, if a woman grows a beard or a man starts speaking in a high-pitched voice, they won’t have anything to do with it. What’s worse: messing with people’s immune systems. How can you force someone to take a vaccine that hasn’t even completed Phase 3 trials yet—one that is still experimental?”
More than ever, the vaccination process in Brazil took on a political tone. The Federative Republic of Brazil shifted from a model of Cooperative Federalism to one of Confrontational Federalism[11], wherein vaccine procurement—an inherently federal responsibility—became fragmented to such an extent that subnational entities formed consortia to facilitate and negotiate purchases on their own. The result? In 2022, the Oswaldo Cruz Institute published an article presenting data on national coverage rates:

“According to Ministry of Health data, vaccination coverage among the population has been plummeting, reaching a point in 2021 where fewer than 59% of citizens were immunized. In 2020, the rate was 67%, and in 2019, it was 73%. The target level recommended by the Ministry of Health is 95%.”

The anti-vaccine movement in Brazil: an import or a local reconfiguration?

Given this scenario, it is worth asking whether the issue of vaccine hesitancy is a phenomenon specific to the Brazilian context or merely a reproduction of what is seen elsewhere. The study by the Laboratory for the Study of Information Disorder and Public Policy[12] shows that this movement—while gaining momentum during the coronavirus pandemic—was not unique to it. In fact, we are dealing with a new context in which scientifically validated information must compete with emotional and religious narratives for the public's perception of reality.

Consequently, anti-vaccine misinformation in Latin America and the Caribbean contributes to the formation of a narrative, emotional, and economic system supported by various actors whose statements and interpretations reinforce one another, since

“[people] find echoes in the words, creating a core group of individuals who know little about anything yet reaffirm each other's beliefs and outlandish theories”

—Cláudio Paixão, PhD in Social Psychology and professor at the UFMG School of Information Science, in an interview with Viva Bem UOL.

Final remarks

First and foremost, it is of utmost importance to mention that all vaccines distributed through the SUS (Unified Health System) have had their efficacy and safety proven and validated by the National Health Surveillance Agency (ANVISA); furthermore, they adhere to World Health Organization (WHO) recommendations and Ministry of Health guidelines. According to the agency, in a news release published in October 2025:

“Immunizing agents are only incorporated into the Unified Health System (SUS) following a rigorous analysis that considers—among other criteria—safety, efficacy, and cost-effectiveness in light of public health needs. All products used in the country undergo quality control by the National Institute of Quality Control in Health (INCQS/Fiocruz).

Furthermore, the safety of vaccines and other immunobiologicals is continuously and systematically monitored through post-marketing pharmacovigilance, carried out through coordinated efforts among manufacturing laboratories, the National Immunization Program (PNI), Anvisa, the INCQS, health departments, and health services and professionals. This coordination ensures the protection of the Brazilian population and maintains public confidence in immunization efforts. Brazil has also been affected by the spread of anti-vaccine rhetoric promoted by various actors—both institutional and non-institutional—many of whom were influenced by international narratives and movements. These narratives often invoked "freedom of expression" to challenge scientific evidence and public immunization policies, contributing to rising vaccine hesitancy in the country. Nevertheless, the latest indicators show a gradual recovery in vaccination coverage. For instance, coverage rates for BCG and Hepatitis B vaccines among newborns surpassed the 95% mark again in 2025.

In such a digital world, there is a need to "know how to play the game" by identifying opportunities beyond standard institutional communication channels—after all, let’s face it: the chances of visibility are far greater when a message is promoted on social media than on a traditional website. In 2022, a section titled "Fact or Fake?" was launched on the Federal Government’s website to verify or debunk claims regarding topics such as agriculture and the fight against environmental crimes. If this institutional editorial approach were expanded beyond the website and integrated into vaccination policies—serving as a form of promotion that simultaneously provides scientifically grounded information and reinforces the importance of vaccination at every stage of life—it could lead to improved coverage rates and a broader audience reach. Furthermore, the Ministry of Health has an asset that could be effectively leveraged, especially in campaigns targeting childhood vaccination: *Zé Gotinha*! This character was created specifically to connect with this target audience, yet has rarely appeared in recent vaccination campaigns.

There is a long road ahead, with a great deal of misinformation to combat. Yet, it is by building brick by brick—and policy by policy—that we move closer to restoring ideal vaccination coverage rates and achieving a population that is immunized, protected, and well-informed.

Isabella Tardelli Maio holds a bachelor's degree in... ...Sciences and Humanities from UFABC; currently pursuing a Master’s degree in Territorial Planning and Management and an undergraduate degree in Public Policy at the same institution. Coordinator and researcher at the Center for Public Policy Analysis and Monitoring (CAMPP).

Giovanna Vitor is an undergraduate student pursuing Bachelor’s degrees in Sciences and Humanities, Public Policy, and International Relations at UFABC. She is a researcher at the Center for Public Policy Analysis and Monitoring (CAMPP).

References

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[1] SILVA, E. C. M.; RICARD, J. C.; ALVES, M. A.; ROCHA, G.; VITÓRIA, S. Vaccine Misinformation in Latin America and the Caribbean. São Paulo – SP, Brazil, Oct. 2025.

[2] KRIZEK, J. P. O. Edward Jenner and the origin of vaccine inoculation. Filosofia e História da Biologia, São Paulo, Brazil, v. 19, no. 1, pp. 31–44, 2024. DOI: 10.11606/issn.2178-6224v19i1p31-44. Available at: <https://revistas.usp.br/fhb/article/view/fhb-v19-n1-02>.

[3] MAGENTA, M. The lessons of the vaccine that arrived in Brazil ‘arm-to-arm’ in 1804. BBC News Brasil. July 25. 2020. Available at: <https://www.bbc.com/portuguese/brasil-53533707>. Accessed on June 24, 2026.

[4] Ibid.

[5] SHATTOCK, A. et al. Contribution of vaccination to improved survival and health: modelling 50 years of the Expanded Programme on Immunization. Available at: <https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(24)00850-X/fulltext>. The Lancet, 2024; 403, 2307-2316.

[6] IDOETA, P. A. The story that gave rise to the myth of the link between vaccines and autism. BBC News Brasil. July 24, 2017. Available at: <https://www.bbc.com/portuguese/geral-40663622>. Accessed on June 26, 2026.

[7] Ibid.

[8] GUEDES, M. J. Anti-vaccine movement: learn what it is and how it emerged. Politize! March 24, 2022. Available at: <https://www.politize.com.br/antivacina/#a-primeira-pratica-de-vacinacao>. Accessed on June 24, 2026.

[9] RO, C. The turbulent history of mandatory vaccination in Brazil and the world. BBC News Brasil. Dec. 4, 2021. Available at: <https://www.bbc.com/portuguese/geral-59424621>. Accessed on: June 25, 2026.

[10] Guedes, 2022

[11] FLEURY, Sonia; FAVA, Virgínia M. D. Covid-19 vaccine: arena of the Brazilian federal dispute. Saúde em Debate, v. 46, no. spe1, pp. 248–264, 2022. Available at: <https://doi.org/10.1590/0103-11042022E117>. Accessed on June 24, 2026.

[12] DesinfoPop/FGV, 2025