DECEMBER 12, 2025 | OPINION | By Kole Petersen
On Nov. 19, the U.S. Centers for Disease Control and Prevention’s (CDC) website was updated with information stating that the link between vaccines and autism spectrum disorder (ASD) has not been ruled out. Despite the mountains of evidence and decades of research pointing to the conclusion that “Vaccines do not cause autism,” the CDC now reports that this is not an evidence-based claim. The U.S. Secretary of Health and Human Services (HHS), Robert F. Kennedy Jr., ordered the website’s alteration and pushed this change without input from the CDC’s developmental disability group. Additionally, they stated that health authorities have ignored studies supporting a vaccine-ASD link. HHS Spokesperson Andrew Nixon said that this update was made to “reflect gold standard, evidence-based science.” However, when asked to provide specific studies supporting their belief, he was seemingly unable to do so.
This practice of simultaneity has defined this administration’s stance on autism spectrum disorder (ASD). They publicly boast about finding the definitive answer to ASD, yet are privately unable to support their claims. However, instead of admitting to the public that they may be wrong and communicating with scientific leaders, the HHS continues to spread their flawed beliefs through highly visible platforms and usurp the process of scientific consensus.
Unfortunately, because many Americans are not well-versed in science, they broadly accept this maliciously formed misinformation. So, let’s dive into this updated webpage and see how the CDC has cherry-picked studies and misreported methodologies to substantiate anti-vaccination mindsets.
Before we begin, it is essential to recognize how the CDC now phrases its claims. They do not outwardly state that vaccines cause ASD, yet the information they present strongly suggests that the current state of science has not ruled this conclusion out. Anti-vaccination groups, including the HHS, have used this linguistic strategy for years; they craft a facade of scientific uncertainty to downplay vaccines’ importance to contemporary human existence. This verbiage satisfies many people’s desires to feel like they know more than those around them, a common trait among conspiracy spheres as a whole.
This knowledge is incredibly valuable when looking at the studies used to cast doubt on infant vaccines. For example, a 2021 Agency for Healthcare Research and Quality (AHRQ) report is listed, which conducted a systematic literature review of the safety of recommended U.S. routine vaccinations, updating the 2014 AHRQ report on the topic. The CDC website claims that this report’s evidence “continued to be insufficient to support or reject a causal relationship between those vaccines and autism.”
Well, I have looked through the report myself, and the CDC’s affirmation is seemingly nowhere to be found. In fact, the report showed a high strength of evidence (SoE) for no increased risk of ASD following MMR vaccines. Indeed, the report clearly outlines that many reviews indicate that the MMR vaccine “is not associated with the onset of autism in children.” For instance, it points to a 2015 study of children born between April 1986 and April 1992 in Japan, a country that used only an MMR vaccine from April 1989 to April 1993. These characteristics make this study’s findings very strong; it found no association between MMR vaccines and ASD up to 36 months in age, and the prevalence of ASD in Japan has not decreased after the MMR vaccine’s discontinuation.
Now, let’s compare this inaccurately reported study with one that the CDC points to as supporting anti-vaccination rhetoric. According to them, a ‘reliable’ cross-sectional study from 2010 found that newborns receiving a Hepatitis B vaccination in the first month of life had a threefold risk of parental report of ASD compared to those who did not get the vaccination or those who did after the first month of life. When trying to access this study for myself, the website on which it was posted stated that it was currently under investigation, a massive red flag that only grew larger as I read through its mind-boggling methodology.
In its results section, the study reports that “boys who received the first HepB dose during the first month of life had 2.82-fold greater odds for autism diagnosis,” then points to a table reporting the odds for autism among participants with an immunization record. This table includes 7,640 children without ASD, 1,258 of whom received the HepB vaccination within the first month of life, and out of only 33 autistic children, just nine received the vaccine during that time frame. That’s right, a total of nine autistic children form the entirety of this study’s evidence of a link between vaccines and ASD.
Even worse, this study did not consider the participants’ medical records when defining vaccination status. Rather, they relied on the handwritten dates marked on the physical vaccination cards that the children’s parents had at home. While this practice is dubious in and of itself, this categorization strategy gets even worse. If either the month or year were missing on the card, that participant’s data was discarded. However, if neither the month nor the year were present, the child was counted as not vaccinated. Thus, children who received the HepB vaccination were considered not vaccinated in this study if there were physical errors on their vaccination cards. This means that the CDC’s claim of a threefold increase is supported by nine autistic children who received a vaccination within a hyperspecific window of time, within a small-scale study with a bafflingly illogical definition of vaccination status, which has never been replicated.
Beyond obscuring faulty research that supports their pre-existing beliefs, the updated CDC website also seeks to delegitimize reputable studies. Notably, they insinuate that a 2002 New England Journal of Medicine study on the Danish population is unreliable, supposedly because Danish children receive immunizations “based on foreign vaccination schedules that differ from the schedule in the U.S.” Before addressing this point, let’s compare the methodologies of this MMR study and the 2010 HepB study. The former consisted of 537,303 children and a populationally representative proportion of ASD-diagnosed children. Meanwhile, the latter had a relevant sample size of 7,673 and a less applicable proportion of autistic participants. Additionally, the former study used MMR vaccination data reported to the National Board of Health, a much more apt definition of vaccination status than physical vaccination cards.
Beyond these apparent disparities in methodological soundness, the fear of unreliability due to “foreign vaccination schedules” is a moot point to make: the MMR vaccination schedules between Denmark and the United States are almost identical. The Danish Ministry of Health currently recommends that children receive their first MMR vaccination at 15 months and their second dose at four years. Meanwhile, the American Academy of Pediatrics recommends the first MMR dose at 12-15 months and the second at four to six years. While it is true that Denmark recommended a second MMR vaccine at 12 years during the 2002 study, only information on the first dose was collected since the later exposure was not relevant to the studied endpoint. Therefore, this variable does not render the 2002 study unreliable for the U.S. population.
Looking at the disparities in the CDC’s characterizations of scientific research and their actual findings calls into question how the former was able to be published. However, as previously mentioned, linguistics, not science, is their weapon of choice. They obscure the lines between a lack of complete scientific certainty and scientific inadequacy. Of course, there is always room for improvement; the 2021 AHRQ report admits that certain studies found insufficient evidence to establish a relationship between a diphtheria vaccine and ASD, and the 2015 Japan study does not guarantee the safety of MMR vaccines. However, touting the impossibility of scientific objectivity is nowhere near the same as lambasting decades of peer-reviewed science through frontages of incompleteness.
Science is based on empirical evidence, which is subject to constant revisions and discoveries. Thus, absolute scientific certainty is impossible; the goal of science is to successively improve our understanding of the world, leading to conclusions that may be almost certain, but not absolutely so. Furthermore, the nature of science means that we cannot technically prove a negative, but we can fail to prove the positive. However, these essential elements of scientific inquiry are not immediately obvious to the general population. It takes time to understand what scientific consensus means, what constitutes a good study and how results can be skewed to fit a pre-existing belief.
This widespread ignorance is exactly why the CDC’s updated website is so dangerous. When science is inaccurately communicated and falsely questioned on a federal level, the American people are led to believe that scientists have been unable to come to a consensus on the vaccine-autism question. For the CDC to blatantly disregard and reinterpret studies is to weaponize Americans’ lack of understanding of scientific jargon. It signifies that we can no longer trust the CDC and the HHS, the entities responsible for providing health and safety information to the public, at face value.
To prevent yourself from falling for similar misinformation in the future, don’t blindly believe what these agencies tell you. Educate yourself on the basics of the scientific method. Read and interpret sourced studies for yourself. And most of all, don’t let this administration fool you into believing that vaccines or ASD are risks to American society.