A large Danish study recently provided reassurance that aluminum-containing vaccines are not associated with increased rates of chronic health conditions in children, including autism. But Health and Human Services Secretary Robert F. Kennedy Jr. misrepresented the study’s findings, claiming that the paper’s supplementary data “shows calamitous evidence of harm.” The study, published on July 15 in Annals of Internal Medicine, drew attention because of its large size and rigorous methods. Anti-vaccine activists, however, quickly seized on it to claim that it was flawed, particularly after the journal mistakenly uploaded an earlier version of the supplementary data. Kennedy declared in an X post last month that the authors used a “long parade of statistical artifices” to “achieve their deceptive results,” incorrectly alleging that the study actually showed an association between vaccines and autism. He linked to an article with his byline on TrialSiteNews, which consisted of a list of criticisms of the study peppered with unfounded accusations on the researchers’ motives. It called for the journal to “immediately retract this badly flawed study.” The journal, however, defended the study. Dr. Christine Laine, the editor-in-chief of Annals, wrote in an editor’s response that the journal found the study “to be among the strongest research currently available” on the subject and that there was no basis for retraction. Small amounts of aluminum are used in some vaccines as adjuvants that boost the immune response and make vaccines more effective. Among those that contain aluminum are vaccines that protect against hepatitis A and B, HPV, and diphtheria and tetanus. There is no aluminum in the measles, mumps and rubella vaccine, which has been subject to unfounded claims about autism in the past. Aluminum has been used as a vaccine adjuvant since the 1920s. The quantities of aluminum in vaccines represent an “extremely low risk to infants,” researchers from the U.S. Food and Drug Administration have concluded. Despite this, aluminum has long been a target of anti-vaccine groups. In the case of the Danish aluminum study, Kennedy dismissed the results of the paper’s main analysis. It found no relationship between aluminum exposure from vaccines and an elevated risk of dozens of conditions, including autism. Instead, he zeroed in on results on autism in two of the paper’s 15 supplementary figures and tables, which he claimed on X were “a devastating indictment of aluminum-containing vaccines directly contradicting the published study’s conclusions.” As we will explain, Kennedy’s interpretation of these figures is unwarranted. For one, statisticians know that if a paper makes a large number of comparisons, some results are expected to be statistically significant by chance alone. It is inappropriate to focus on a single result or subset of results while ignoring their context. Kennedy “is doing extreme cherry-picking of the results he likes and ignoring and dismissing all of the results he doesn’t like,” Jeffrey S. Morris, director of the division of biostatistics at the University of Pennsylvania’s Perelman School of Medicine, told us. For another, Kennedy highlighted an analysis that the authors of the paper and other experts said should not be used to determine whether aluminum in vaccines causes health conditions. “In short, Kennedy is cherry-picking a fragile secondary analysis that is explicitly disclaimed by the study’s authors and misrepresenting it as a refutation of the main findings,” vaccinologist Helen Petousis-Harris of the University of Auckland told us in an email. “It’s a classic misuse of supplementary data.” She called the supplementary results Kennedy highlighted a “statistical blip, not a bombshell.” Anders Hviid, head of the epidemiology research department at the Statens Serum Institut in Denmark, agreed that Kennedy’s interpretation of his team’s study amounted to cherry-picking. “Our results showed that increasing exposure to aluminum from vaccines was not associated with increasing risks of a wide range of early childhood health conditions in Denmark,” he told us in an email. Kennedy’s statements followed a pattern familiar to those who have tracked the secretary’s history of unfounded claims on vaccines and autism. Historically, Kennedy has ignored or attempted to discredit well-done scientific studies that have failed to show a link between autism and vaccination. His criticisms are often accompanied by inflammatory language and unfounded claims about researchers’ motivations. At the same time, he has zeroed in on results that he claims show an association, elevating flawed studies and highlighting decades-old unpublished statistics that weren’t borne out by later analysis. HHS did not reply to a request for comment. ‘The Cherry-Pick of All Cherry-Picks‘ Denmark’s universal, publicly funded health care system and detailed record-keeping allow researchers to study the relationship between medical care and health outcomes. Hviid and his colleagues analyzed vaccination and health data on more than 1.2 million children who were born in the country over the course of around two decades. As the Danish vaccine schedule changed over time, the amount of aluminum in recommended vaccines also changed, allowing the researchers to assess whether each additional milligram of aluminum exposure had any relationship to chronic disease. Photo by lavizzara / stock.adobe.com In their primary analysis, the researchers found no link between the amount of aluminum the children received via vaccination and elevated rates of 50 chronic conditions. These conditions included asthma and allergic diseases, autoimmune diseases, and neurodevelopmental conditions. This last group of conditions included attention-deficit/hyperactivity disorder and five autism-related diagnoses. “The main findings, based on solid methods and all the data, showed no increased risk,” Petousis-Harris said (emphasis is hers). Rather than highlighting these reassuring results, Kennedy focused on a supplemental figure showing a barely statistically significant increase in one autism-related diagnosis in a single set of children. “The data show a statistically significant 67% increased risk of Asperger’s syndrome per 1 mg increase in aluminum exposure among children born between 2007 and 2018,” Kennedy wrote on X. (In the U.S., Asperger’s syndrome is no longer a specific diagnosis. The condition was folded into the autism spectrum disorder diagnosis in 2013 in the fifth edition of the American Psychiatric Association’s Diagnostic and Statistical Manual of Mental Disorders.) “That is the cherry-pick of all cherry-picks,” Morris said. The figure was part of a series of analyses meant to look at the data in various ways and see if the primary results held up — and hold up they did, in almost
