Recent research challenges Kennedy’s claims about vaccines, Tylenol and antidepressants
Highlights from Health Secretary Robert F. Kennedy Jr. and his superiors: Taking Tylenol while pregnant may be linked to autism. Antidepressants may be dangerous during pregnancy. Aluminum salts in vaccines can be dangerous to health. And the images of Covid are not good for healthy children.
These claims caused confusion last year, as scientists warned there was no evidence to support them. However, health organizations follow policies based on what is said.
Now, a slew of new research released in the past few months offers the strongest rebuttal to date.
The latest finding came this month: After Food and Drug officials questioned the safety of taking antidepressants while pregnant, a new study presented at the annual meeting of the Society for Maternal-Fetal Medicine found that pregnant patients who stopped taking the medication nearly doubled their risk of mental health-related emergency room visits.
Another recent study also found that aluminum salts in vaccines are not linked to major safety concerns and that the Covid shot has a protective benefit for children.
Some papers were started in response to Kennedy’s and the White House’s statements, while others were already underway.
“These are just the latest examples in a decade-long history of Secretary Kennedy making claims about vaccines that are contradicted by facts and data,” said Michael Osterholm, executive director of the University of Minnesota’s Vaccine Integrity Project, in a statement. The project was launched after Kennedy’s commitment to create an independent, transparent process for evaluating vaccine safety, he said.
Emily Hilliard, a spokeswoman for the Department of Health and Human Services, said in a statement that “HHS remains focused on rigorous scientific review, transparency, and ensuring the continued safety and effectiveness of the US vaccine offering.”
The Trump administration has pledged to conduct its own “gold standard” studies on vaccine safety and the causes of autism, among other topics of interest to Kennedy. But those studies are not yet available — and many public health experts question whether they will be biased if they do. (Decades of research have established a link between vaccines and autism.)
Already, some of the administration’s loudest claims about drugs and vaccines have become official positions of federal health agencies: The Centers for Disease Control and Prevention stopped recommending the Covid shot for healthy babies last year, and in September, with Kennedy standing behind him, President Donald Trump told pregnant women to “fight like hell” not to take Tylenol.
What is safe to take while pregnant?
In the past year, several top health officials have warned of the potential dangers of taking Tylenol and antidepressants while pregnant. But the latest evidence released since January does not confirm those concerns.
The FDA convened a panel in July where nearly all panelists raised concerns about pregnant women choosing serotonin reuptake inhibitors — a class of antidepressants that includes Lexapro, Prozac and Zoloft. This decision was against the recommendation of the American College of Obstetricians and Gynecologists that pregnant patients stay on medication. Psychiatrists strongly criticized this event.
FDA Commissioner, Dr. Marty Makary, said during the panel that SSRIs may lead to birth defects and questioned their efficacy, saying “the more antidepressants we give, the more depression we get.” Some panelists also called for stronger warnings on SSRI drug labels.
Hilliard told NBC News that “the FDA will review the data and revise product labels accordingly” if high-quality studies show safety concerns beyond what is stated on the labels.
SSRI labels currently refer to the potential risk of severe bleeding known as postpartum hemorrhage in the mother or a life-threatening breathing problem called persistent pulmonary hypertension in the newborn. However, evidence shows that those risks are small, especially when compared to the risks of depression itself.
“Generally, we don’t think it’s so dangerous that we would ever recommend a patient to stop their medication because of it,” said Dr. Kelly Zafman, an obstetrician at the Hospital of the University of Pennsylvania.
On its own, untreated stress can increase the risk of premature birth and preeclampsia. Scientists also haven’t found strong evidence that SSRIs are linked to autism or birth defects.
Zafman released a new study this month that analyzed the health insurance claims of nearly 4,000 patients with depression or anxiety who took antidepressants before they became pregnant. Of the women who stopped using antidepressants during pregnancy, 1,357 had a mental health-related ER visit, compared to 795 who stayed with their prescriptions.
Zafman said some ER visits may be related to drug overdoses, suicide attempts or debilitating insomnia, though insurance information does not specify the type of mental health emergency. Many of these problems can be life-threatening for a child.
The most common drug sometimes taken during pregnancy, Tylenol, also does not pose the risks described by Trump and Kennedy.
The pair warned in September about a possible link between Tylenol in pregnancy and autism in children. Makary also told doctors in a written notice to “consider reducing the use of acetaminophen,” the active ingredient in Tylenol.
Hilliard, the HHS spokeswoman, said many experts have expressed concern about using acetaminophen during pregnancy. However, hard scientific evidence does not support the claim. Kenvue, the maker of Tylenol, said research shows that acetaminophen does not cause autism, and urged US regulators not to put an autism warning label on the drug.
A group of researchers tried to clear up the confusion last month by publishing another well-researched paper on the subject. The team excluded studies with evidence of bias, such as those that did not follow study participants long-term or disclose the health histories of pregnant women. They found no link between acetaminophen use in pregnancy and neurodevelopmental disorders, including autism.
“We know that autism is a complex interaction between hundreds of genes and environmental factors early in pregnancy,” said Dr. Peter Hotez, director of the National School of Tropical Medicine at Baylor College of Medicine in Texas and co-director of the Texas Children’s Hospital Center for Vaccine Development.
Certain chemical exposures early in pregnancy can interact with autism genes, Hotez said, but Kennedy “isn’t interested in testing that.”
Vaccines: Perceived risks and demonstrated benefits
In September, the CDC officially changed its Covid vaccination guidelines to recommend that people decide with their doctors whether to get the shots. In recent months, Kennedy, Makary and Dr. Jay Bhattacharya, the director of the National Institutes of Health, said that the organization will no longer recommend the Covid vaccine for healthy children and pregnant women.
In a video on X announcing the change, officials say there is no evidence to support giving children Covid boosters. The FDA’s top vaccine administrator, Dr. Vinay Prasad, also told staff last fall that the Covid-19 vaccine had killed at least 10 children – but did not provide evidence, such as death certificates, to support the claim.
The CDC’s own research has consistently found that Covid vaccines and the booster shot protect against serious illness in children. Most recently, a CDC study in December found that the Covid vaccines given from 2024 to 2025 reduced the risk of Covid-related emergency room and emergency visits by 76% among children aged 9 months to 4 years and 56% among children aged 5 to 17 years.
Kennedy, who has a history of fighting vaccines, called the 2021 Covid vaccine “the deadliest vaccine ever made.” In June, he fired former members of the CDC’s vaccine advisory team and replaced them with a group that was more skeptical of the Covid shot.
Under his leadership, HHS is investigating whether aluminum salts in vaccines may be linked to autism, according to a statement posted on the CDC website in November. Trump said in a press conference last year that aluminum “is being taken out of vaccines,” adding: “Who the hell wants to put it in the body?”
Aluminum salts – naturally present in soil and water – are added to vaccines to enhance the body’s immune response, allowing a smaller dose to be used. About a hundred proofs have been found safe for that purpose. Many childhood vaccines in the US contain aluminum salts, including those for hepatitis A and B, HPV, meningitis and whooping cough.
However, aluminum salts have been the target of many anti-vaccination activists. Kennedy told nutritionist Mikhaila Peterson in 2021 that the brains of children with autism were “full of aluminum.”
A December analysis in the journal Pediatrics reviewed the available evidence regarding the growing vaccine skepticism. The researchers did not find any major safety concerns related to aluminum salts in vaccines.
“This is kind of the playbook for Kennedy. He never followed the science,” Hotez said. “You can throw all the evidence you want at him and he doesn’t care. It’s all about picking up whatever he thinks supports his agenda.”
