At the beginning of the month, U.S. President Donald Trump signed an executive order aimed at reducing the number of recommended childhood vaccines in the country. In addition to separating the measles, mumps, and rubella (MMR) vaccine into individual doses, the executive order removes vac…
Decisions Without a Scientific Basis Rekindle the Risk of the Return of Eradicated Diseases
At the beginning of the month, U.S. President Donald Trump signed an executive order aimed at reducing the number of childhood vaccines recommended in the country. In addition to splitting the measles, mumps, and rubella (MMR) vaccine into individual doses, the executive order removes vaccines against COVID-19, influenza, rotavirus, hepatitis A, hepatitis B, bacterial meningitis, and respiratory syncytial virus (RSV). “It is not just about reducing the number of vaccines or injections, but rather administering them over a series of visits,” Trump said, suggesting that the MMR vaccine could be “quite lethal” if administered all at once, without citing any research or scientific evidence.
According to the U.S. Centers for Disease Control and Prevention (CDC), “there is no published scientific evidence demonstrating any benefit to separating the MMR vaccine into three individual doses.” The World Health Organization (WHO), an organization the U.S. left during the Trump administration, said that the changes announced by the White House are not based on established scientific evidence and that delaying doses could leave millions of children unprotected. The president and the government’s Health Secretary, Robert F. Kennedy Jr., have also again linked vaccines to autism, a theory that has been widely refuted by science.
Vaccines are safe
According to Marta Lopes, an infectious-disease physician, senior professor at the University of São Paulo Medical School (USP), and adviser to the State of São Paulo’s Permanent Immunization Advisory Committee (CPAI), the government’s decision is unusual, but she emphasizes that it does not have the force of law.
“It is as if, in any country in the world, regardless of its regulatory bodies, such as Brazil’s National Immunization Program (PNI) or the Centers for Disease Control and Prevention in the United States, the government official of the day were to make decisions disregarding the bodies where decisions about vaccines, health, and science have traditionally been made.”
Although families are not required to follow the recommendations, such suggestions can affect many American families and lead to misinformation or vaccine hesitancy, potentially exposing large numbers of children to preventable diseases, the professor explains.
“A vaccine is recommended based on a series of studies, research, and discussions carried out over many years, taking into account the burden and cost of the disease. Purchasing and distributing vaccines prevents hospitalizations and deaths and reduces the human and financial costs to the country. A patient may still come into contact with the virus, but will develop a milder form of the disease,” she explained.
Denise Morais da Fonseca, a professor in the Department of Immunology at USP’s Institute of Biomedical Sciences, said the change is surprising because vaccination plans and schedules are designed based on the pathogens circulating in society, as well as their severity and risk.
“Nothing is developed randomly. From my point of view, this recommendation is not appropriate. Vaccinations against diseases that cause substantial morbidity, particularly in children, have been removed from the vaccination schedule. Rotavirus, hepatitis, bacterial meningitis, and respiratory syncytial virus have been removed. RSV is widely circulating and is responsible for many childhood hospitalizations. Removing these vaccines makes no sense, especially because these diseases are still circulating.”
The professor also explains that claims about the risks of vaccines are unfounded.
“There is no scientific paper published in a recognized, reputable journal respected by the scientific community proving a relationship between vaccines and autism,” she emphasized.
A study conducted in Denmark evaluated more than half a million children according to sex, weight, gestational age at birth, age at autism diagnosis or related conditions, families’ socioeconomic circumstances, and the mother’s educational level. The authors concluded that there was no increase in the development of autism or other autism-spectrum-related conditions when comparing children who received the MMR vaccine with those who were unvaccinated.
Denise reiterates that combining vaccines increases uptake and significantly reduces the risk of people failing to complete vaccination.
“If we combine three vaccines into a single shot, only one trip to the health clinic is necessary. The child’s father, guardian, or even the adult receiving the vaccine has to set aside time and wait in lines. There are also production, storage, administration, and material costs. All of these factors make combination vaccines very sensible, in addition to the fact that their side effects have been exhaustively tested. It has already been established that there is no difference in side effects whether they are administered separately or together.”
Marta highlights the greater comfort for recipients, operational advantages, and safety of combination vaccines that are available and already widely used.
“Three injections are much more uncomfortable for a child, and for the person accompanying the child, than a single ‘little shot.’ For vaccines to reach this formulation, extensive research was conducted in different populations and using different schedules to test their efficacy and safety. The MMR vaccine officially entered Brazil’s PNI in 1992; it has been distributed on a large scale for more than 30 years. In addition to the studies testing safety and efficacy, we have important real-world experience. These vaccines are well established as safe and effective.”
How a vaccine is developed
A vaccination schedule is developed based on scientific evidence concerning the incidence, prevalence, burden, and consequences of a disease, with the goal of improving quality of life for different age groups, Marta explains.
“Each country has its own particularities, but the groups involved are predominantly the country’s public-health authorities. In Brazil, for example, they include the Ministry of Health, the Department of the National Immunization Program (DPNI), the Technical Advisory Chamber on Immunizations (CTAI), Brazilian medical societies, among other groups, always supported by experts and serious studies.”
The CTAI consists of representatives of Brazil’s National Health Surveillance Agency (Anvisa), federal and municipal health councils, members of scientific societies, specialists, epidemiologists, infectious-disease physicians, researchers, and other authorities. Linked to the Ministry of Health, it assesses epidemiological conditions: which pathogens are currently circulating, the severity of diseases, and mortality. It advises the National Immunization Program on decisions such as introducing vaccines, recommending the best age groups for vaccination, determining the number of doses, and other factors that ensure safety and maximum efficacy.
“All these analyses are carried out in light of science, scientific data, and epidemiological data. A country’s vaccination schedule is not something the president decides or that can be delegated to a single person.”
Ana Paula Sato, a member of São Paulo’s Permanent Immunization Advisory Committee and a professor in USP’s Department of Epidemiology at the School of Public Health, explains that vaccine development follows rigorous scientific, ethical, and regulatory standards.
“Product development goes through preclinical stages and clinical phases involving human studies to establish the vaccine’s safety, immunogenicity, and efficacy, followed by licensing assessments by regulatory agencies such as Anvisa in Brazil. Even after a vaccine is released onto the market, it continues to be evaluated for safety and effectiveness in what is known as Phase 4 or pharmacovigilance,” the professor explained.
Ana Paula also noted that every batch of immunobiological products is evaluated by Brazil’s National Institute for Health Quality Control (INCQS) before being used.
“Any events supposedly attributable to vaccination or immunization are systematically assessed and discussed. The safety profile of vaccines is closely monitored from development through their use in the population, whether by the manufacturer or by the health system through the immunization program or regulatory agency,” Ana Paula emphasized.
Marta reiterates that, to be used in Brazil, a vaccine must go through all of Anvisa’s approval steps, even if it has already been approved in another country.
“A vaccination schedule cannot simply be imported. Differences between vaccines recommended in different countries and regions are predominantly due to the disease burden and how significant the disease is from a public-health perspective,” the professor explains.
Collective protection and cost-effectiveness
Amid statements downplaying the importance of vaccination and questioning the efficacy and safety of vaccines, the United States is experiencing its worst measles outbreak in 35 years. There are more than 2,300 confirmed cases of a disease that the country considered eradicated at the beginning of the century.
Kennedy Jr. defended the proposed changes by saying they are intended to give parents a choice, rather than prohibit access to childhood vaccines. Marta emphasizes that vaccination is fundamentally a collective measure, not simply an individual choice.
Vaccination saves lives and prevents the return of diseases that have already been controlled
Experts stress the importance of keeping vaccination records up to date and the need to increase vaccination coverage among vulnerable groups.
“Whether people acknowledge it or not, vaccination involves a collective process. When someone chooses not to vaccinate their child, or chooses not to get vaccinated against measles, for example, they are taking the risk of contracting measles. The disease may or may not be severe for that individual, but they become a transmitter of measles. Measles is highly transmissible; it is estimated that one person with measles can infect up to 18 susceptible people,” she said.
The greatest concern involves pregnant women, older adults, immunocompromised people, and other at-risk groups who may not be able to receive certain vaccines. This “individual decision” affects other people’s health because of the individual who chose not to protect themselves against the disease.
Denise discusses the “herd effect” of immunization, which provides collective protection.
“When you get vaccinated, you are protecting someone who cannot be vaccinated because you reduce circulation of that pathogen. A pregnant woman who contracts measles, for example, can transmit the disease to the fetus, causing irreversible harm and even fetal loss. The same applies to immunosuppressed people who cannot be vaccinated. We need to get vaccinated not only to protect ourselves, but to protect society as a whole.”
Beyond the health benefits, most vaccines and immunizations also offer an economic advantage compared with the cost to the public-health system of treating the diseases and their consequences.
Denise highlights the costs associated with COVID-19 and polio as examples of the cost-effectiveness of vaccines:
“During the pandemic, people spent days or weeks hospitalized in intensive care units, on artificial ventilation. One vaccine dose costs only as much as a single day in an ICU. Polio causes severe motor disabilities in children and can impair breathing. Immunization prevents expensive, lengthy hospitalizations, the development of disabilities, and the use of ventilators, while greatly reducing the chances of developing severe disease.”
The number of unvaccinated children in Brazil has more than doubled
Experts point to misinformation and lack of investment as the main causes of the decline in childhood vaccination coverage.
Conspiracy theories and misinformation explain vaccine hesitancy in Portuguese-speaking countries
A survey questioned 6,843 people from Portugal, Brazil, and African countries between May and August 2020. Among those interviewed, 21.1% (1,443 people) said they did not intend to get vaccinated.
A study by the Bloomberg School of Public Health found that in 2015 alone, approximately US$9 million was spent in the United States on vaccine-preventable diseases, in a study covering ten types of vaccines recommended for adults aged 19 and older.
Marta explains that as vaccination succeeds, diseases become increasingly rare; because of this tremendous success, people also begin to forget about the diseases, leading to a wave of downplaying their importance.
“They have lost their fear. They want to replace immunization with natural approaches, a good diet, and healthy practices, which are important but unfortunately are not sufficient to control these diseases.”
The professor argues that Brazil, despite also experiencing the effects of vaccine hesitancy and anti-vaccine movements, has a vaccination tradition that has endured.
“Vaccination coverage declined. It began before the pandemic, but during the pandemic it was disastrous. We are recovering coverage levels; we have not reached the ideal coverage we would like, but we are on the way,” Marta says.
Denise reiterates the importance of Brazil’s National Immunization Program and says it is a model of immunization for the world.
“The PNI has existed for more than 50 years. It distributes a range of vaccines, sera, and immunoglobulins, all free of charge.”
The professor also highlights Brazil’s capacity for vaccine research and production:
“We produce vaccines at the Butantan Institute and Bio-Manguinhos, and we also have a great deal of basic research. We still have difficulty conducting clinical trials, which require very large financial investments, but we are certainly a global reference in immunization.”
Marta emphasizes the role of Brazil’s Unified Health System (SUS) and the PNI:
“Immunization is not simply about giving a vaccine. It has to be distributed, stored at controlled temperatures, and administered by trained people who can explain the indications and contraindications to the population. All this infrastructure is important and continues to improve with the development of the SUS. We do not have every vaccine available—no country does. But we had the critical judgment to determine which were the most important and the most accessible to purchase and maintain vaccination.”
“We need programs with longevity. The PNI is an example of this, the result of the efforts of several pioneers in public health and vaccinology.”
Misinformation
It has never been easier to search for and find information, but it has also never been harder to verify information sources, Denise comments.
A USP study analyzed the risks associated with vaccines and the effects of not vaccinating on the global population through a literature review and analysis of outbreaks caused by lack of vaccination. In addition to concluding that there is no causal relationship between vaccination and autism, Alzheimer’s disease, or narcolepsy, the study warns of a new challenge: lack of information and the dissemination of non-scientific information have contributed to the re-emergence of infectious diseases in various countries and threaten global plans to eradicate infectious diseases.
“At the same time that we have access to correct, well-founded information, we also have access to incorrect, unfounded information. Not only in healthcare, but in every field.”
Beyond strengthening anti-vaccine movements, scientifically unfounded attacks on vaccine safety made by world political leaders also reinforce vaccine hesitancy.
Marta argues that healthcare professionals need to make the case for vaccination, encourage people to listen, and earn their trust to ensure vaccination.
“We need to welcome a mother who does not want to vaccinate her child with a particular vaccine and understand her motivations. By doing so, we open a dialogue to explain the advantages and safety of vaccination and reach an agreement.”
The professor also reiterates the importance of using official channels of scientific organizations to communicate knowledge.
“We need to make use of all the communication channels available today to disseminate information and respond appropriately, without criticism, to all questions that arise,” she said.
Denise stresses the importance of scientific communication by research institutions and of developing vigilant strategies to check information published on social networks.
“Investment in science journalism needs to increase so that more qualified people can seek out, check, and validate information. This would allow us to combat and directly confront misinformation.”
USP researchers analyzed studies on communication methods and strategies related to childhood vaccine hesitancy to understand how these factors influence the decisions of parents and caregivers. They concluded that health communication is fundamental to addressing hesitancy and that integrated strategies combining evidence-based public policies with personalized and culturally sensitive communication are essential to promoting vaccination uptake and greater confidence in vaccines.
“The relationship people have with healthcare professionals is essential to increasing confidence in and uptake of vaccines. Therefore, the training and continuing education of healthcare professionals about vaccines and vaccination must be strengthened.”
*Under the supervision of journalists Paulo Capuzzo and Cinderela Caldeira.
