By Tiago Tasca, Ph.D. Candidate in the Politics Department at UC-Santa Cruz
The Americas have historically been successful in eliminating numerous diseases, as evidenced by the successful campaign against poliomyelitis, a disease that causes infant paralysis, in the 1990s. Among Latin American countries, Brazil stands out for its high vaccine acceptance rates, strong community support, and a deeply ingrained culture of vaccination. Brazil’s public health system, the Sistema Único de Saúde (SUS), is globally recognized as free, universal, and highly decentralized. This system, a landmark of Brazilian democracy in the late 1980s, was significantly influenced by social movements in the 1970s and 1980s known as the Sanitaristas. This movement has focused on primary healthcare, emphasizing preventive measures and addressing social determinants of health rather than concentrating solely on curative, doctor-centered, or disease-focused approaches. Its strong focus on primary healthcare and prevention has placed vaccinations at the core of Brazil’s public health strategy, as they are critical for protecting the population and promoting overall well-being.
Although vaccines have proven to be a highly successful intervention in eliminating and eradicating diseases over the centuries, recent years have seen a growing number of people in Brazil and beyond who are becoming hesitant or refusing vaccination for various reasons, including fear of needles, fear of side effects, belief in conspiracy theories (e.g., increased belief that vaccines changing people’s DNA), religious beliefs, and other concerns. Vaccine hesitancy can be defined as a delay in acceptance, outright refusal, or selective acceptance of certain vaccines and is now a global issue with severe consequences, posing significant challenges for many countries with the threat of the re-emergence of diseases already eradicated. For example, nearly four decades after Brazil was certified as polio-free, following many years of maintaining high vaccination rates for vaccine-preventable diseases, a recent study from the Pan-American Health Organization (PAHO) revealed that in 2024, around 68% of Brazilian municipalities are now classified as high or very high risk for the return of poliomyelitis, and 86% for measles. The decline in vaccination rates has led to several epidemiological repercussions. For instance, in 2018, when vaccines were abundant across Brazil, the country lost its measles-free status following an outbreak. According to UNICEF, by 2021, Brazil was ranked among the top 20 countries with the highest number of “zero-dose” children. What explains this decline? Is access to vaccination sites limited? Has the COVID-19 pandemic led to a general loss of trust in immunizations? And what role do fake news, misinformation, voting behavior, and conspiracy theories about vaccines play in this scenario? These questions have fueled my curiosity to understand the factors behind this worrying trend in Brazil’s immunization coverage.
With these questions in mind, I spent this past summer investigating the downfall in vaccination rates in Southern Brazil, a region composed of three states (Paraná, Santa Catarina, and Rio Grande do Sul). This region has solid socioeconomic indicators—such as higher GDP per capita and a lower Gini index in comparison to other Brazilian states—where one might expect better healthcare outcomes, including robust immunization rates, due to higher state capacity in providing healthcare services (e.g., health professionals per inhabitant, better physical and bureaucratic infrastructure, etc.). Despite these indicators, the region has seen its lowest vaccination rates in decades.
To explore this phenomenon, I have adopted a mixed-methods approach, combining three primary data collection strategies. First, I conducted surveys to examine individual-level reasons for vaccine hesitancy, particularly focused on political ideology, belief in pieces of misinformation, and trust in institutions. For example, does vaccine hesitancy differ between individuals aligned with left- or right-wing political parties? And how does trust in institutions affect people’s vaccine uptake? I also assessed the degree of belief in conspiracy theories (e.g., vaccines related to infertility, vaccines as a government conspiracy to sterilize marginalized people) and sociodemographic data. Second, I conducted over 100 interviews with healthcare professionals, including physicians, nurses, technicians, community health workers, dentists, policy experts at the state and federal levels, and health secretaries. Third, I gathered official data from the Brazilian government to understand changes in subnational state capacity to deliver primary healthcare. Besides some interviews in Brasília, where the Ministry of Health is located and where many policy guidelines about vaccines and primary healthcare originate, I also spoke with people in twenty-four municipalities with populations ranging from 3,000 to 500,000 inhabitants. I connected with key stakeholders, such as the National Council of Health Secretaries (CONASS) and the National Council of Municipal Health Secretaries (CONASEMS), who outlined their main strategies to restore high immunization rates nationwide. The Dolores Huerta Graduate Student Award funding was crucial for me to conduct these interviews and connect with different municipalities and governmental agencies to schedule further interviews in the coming months.
During these interviews, the informants described the decline in immunization rates as a multifaceted problem. Contributing factors include a rise in belief in fake news, reduced perception of risk (for example, when a disease is no longer prevalent, people may feel less urgency to vaccinate against it), and systemic issues with information systems (such as unstable internet connections and frequent software changes for recording immunization data). Additionally, the uncertainties surrounding COVID-19 created broader fears around other vaccines. Regarding individual-level factors, interviews have revealed how people’s experiences with government institutions can compound when political leaders use anti-establishment rhetoric to undermine trust in institutions, including public health agencies responsible for delivering essential services like vaccinations. Given that SUS is tasked with providing vaccines to the entire Brazilian population, any erosion of trust in SUS can seriously affect the country’s vaccination efforts and foster the reintroduction of diseases already eradicated and eliminated, such as poliomyelitis.
These initial findings align with what several health professionals have highlighted as the political roots of vaccine hesitancy in Brazil, specifically the politicization of vaccines. In a highly polarized political environment between right- and left-wing parties, vaccination policies have faced significant challenges. Vaccine politicization is a relatively new phenomenon in Brazil, emerging during the COVID-19 pandemic, where the COVID-19 vaccines became central to the political debate. Informants have suggested that political factors help explain vaccination rates, with distrust in the government playing a significant role. For example, some community health workers reported that some patients believe the COVID-19 and influenza vaccines are part of a government experiment aimed at reducing the elderly population to ease the burden on social security.
Another significant finding from this research is the link between voting for the far-right candidate in the 2022 presidential elections (Jair Bolsonaro, from the Liberal Party) and increased vaccine hesitancy. In Brazil’s polarized political environment, where two leading parties have dominated the electoral landscape at the federal level, partisan affiliations influence people’s attitudes toward vaccination. Interviewees say vaccine politicization occurs when political leaders and parties transform vaccination into a political issue. This phenomenon, which emerged during Bolsonaro’s administration, was previously unheard of in Brazil, according to many of my informants. Although vaccine hesitancy existed before COVID-19, such as with the HPV vaccine due to moral and religious reasons, it was not previously associated with any political party or candidate.
During his time in power, Bolsonaro spread numerous fake news reports about vaccines, including when he falsely asserted that individuals were developing HIV/AIDS after receiving their second dose of the COVID-19 vaccine. In another controversial statement, Bolsonaro quipped that it would be their responsibility if someone turned into a crocodile after being vaccinated. Many interviewees noted that vaccine-hesitant individuals often referenced Bolsonaro’s remarks, particularly emphasizing that he did not get vaccinated. Common sentiments included statements like, “If the vaccine were effective, why didn’t the president take it?” Moreover, the populist right-wing parties in Brazil have discredited many scientific institutions, such as Brazilian public universities and research institutes such as the Fundação Oswaldo Cruz (Fiocruz), as ill-equipped to deal with pressing national issues. These criticisms have deleteriously impacted people’s institutional trust, which is crucial for the success of preventative healthcare.
During my fieldwork, I have come across many different voices and opinions about vaccines and primary healthcare. It has been eye-opening—and sometimes difficult—to navigate the range of perspectives. During some interviews, people have questioned and challenged me in different ways. These conversations are only possible because I have taken the time to meet people where they are—people who interact with healthcare systems daily, either as providers or patients.
Digging into how people feel about biomedical interventions, especially in their local context, has shown me so much about the cultural and moral complexities people face. Given my genuine belief in primary healthcare as a key driver for improving people’s well-being and life conditions, I am constantly interested in comprehending how social and political issues impact a wider range of preventative health services. As we just saw with the COVID-19 pandemic, politics has defined the contours of health interventions, and political decisions have determined the fate of millions of people worldwide. It is even more evident to me now that if we do not understand the environment people live in—their daily struggles, fears, viewpoints, and beliefs—we will not be able to design and, most importantly, implement social policies that work for them.