Antivaccine nonsense Bad science

Will COVID-19 vaccines drive an “epidemic of autism”? No, but Byram Bridle thinks so.

Antivax scientist Byram Bridle parties like it’s 2005 and asks if COVID-19 vaccines might cause an “epidemic of autism.” Everything old is new again, sort of.

Sometimes there are topics that just demand that I write about them. So it was that when I saw the “target” of today’s post, I knew I had to write about this was because it so clearly vindicated what for me had started out as a bit of a quip that I had started repeating in the early months after the mRNA-based COVID-19 vaccines from Pfizer and Moderna first rolled out in those heady days of early 2021, namely that the only reason antivaxxers weren’t claiming that COVID-19 vaccines could cause autism was because they were not being administered to young children. As the age range for the COVID-19 vaccines got younger and younger, I predicted that antivaxxers would soon be blaming them for autism, but that it might take a few years because autism spectrum disorders are usually not diagnosed until a child is around 3 years old and the characteristic behaviors start to manifest themselves to the point where the parents become concerned. Leave it to Byram Bridle to vindicate my prediction with a post over the weekend on his Substack entitled Will COVID-19 Shots Drive an Epidemic of Autism?, albeit not in the way that I expected. He did, however, echo a common variant of an old antivax claim that vaccines cause autism by adding the blurb If Yes, Those Who Coerced Pregnant Women to Take modRNA Shots Will Be Responsible For It.

It all very much reminded me of something I said on X, the platform formerly known as Twitter, a week ago:

Byram Bridle returns! (He never really went away)

You might remember Dr. Byram Bridle, associate professor and viral immunologist in the Department of Pathobiology in the Ontario Veterinary College at the University of Guelph, from the early days of the COVID-19 vaccine rollout nearly three years ago. I first wrote about him in June 2021, when he claimed to have “discovered” a “secret” Japanese study that showed that the Pfizer vaccine’s biodistribution included the ovaries (among other organs), ignoring the facts that the study was not “secret” and was a fairly standard biodistribution study in which huge doses of the vaccine were injected intravenously in mice in order to determine where the drug might go, no matter how small the quantities. (Remember, vaccines are not injected directly into the bloodstream, much less at doses anywhere near what the study used.)

At the time, I also took note of Dr. Bridle for videos like this:

Basically, Dr. Bridle (mis)represented himself as a “provaccine” scientist who made this startling admission (tellingly, quoted by Mike Adams):

In short, the conclusion is we made a big mistake. We didn’t realize it until now. We saw the spike protein was a great target antigen. We never knew the spike protein, itself, was a toxin and was a pathogenic protein. So, by vaccinating people, we are inadvertently inoculating them with a toxin, and in some people this gets into circulation. And when that happens in some people, it can cause damage, especially with the cardiovascular system. I don’t have time, but many other legitimate questions about the long-term safety there for this vaccine. For example, with accumulating in the ovaries, one of my questions is, “will we be rendering young people infertile, some of them infertile?” So, I’ll stop there.

Yep, it’s the “vaccines are going to sterilize our womenfolk” gambit all over again, an antivax gambit that started right around the time that COVID-19 vaccines were granted emergency use authorization (EUA) in December 2020. It’s a very old antivax trope that dates back decades, which is why I was not surprised to see it rear its ugly head again applied to the new mRNA-based vaccines. How old is it? Well, as a matter of coincidence, a peer-reviewed article co-authored by Tara Smith and me accepted for publication in Vaccine just hit the journal’s website late last week. (That’s the first good thing that’s happened to me in 2024.) In the article, we discuss how this trope goes back at least to the 1990s and why it’s a nonsensical conspiracy theory.

But back to Dr. Bridle, given that this time he is not fear mongering about COVID-19 vaccines “sterilizing the womenfolk.” During the last three years, he has diversified his antivax propaganda; for instance, by sarcastically fear mongering about mRNA in breast milk, credulously accusing “Them” of “suppressing” data supposedly showing that ivermectin works against COVID-19 (it doesn’t), parroting the antivax line about “adulteration” of mRNA-based vaccines with plasmid DNA (which is a big nothingburger), and showing up at all sorts of conspiracy theorist antivax conferences and panels. Basically, as much as he claims to be “not antivax,” by his words and actions Dr. Bridle has demonstrated himself to be very much antivax indeed, right up to amusingly whining about how provaccine scientists (like Timothy Caulfield) and advocates “won’t debate him.”

COVID-19 vaccines and autism?

Based on his history, it should come a surprise to no one that Dr. Bridle finds a study done in rats very persuasive support for the contention that prenatal exposure to COVID-19 vaccines will cause autism. It should also come as no surprise given the long history (some of which I myself have documented here) of antivax scientists doing dubious studies of vaccines or vaccine ingredients, like the mercury-containing preservative thimerosal back in the day when thimerosal-containing vaccines were demonized as The One True Vaccine Cause of Autism, at least here in the US. Dr. Bridle’s post also reminded me of a number studies cited by antivaxxers to claim that “immune activation” due to prenatal exposure to, say, Tdap vaccines during pregnancy can hugely increase the risk of autism in the child after birth. (They don’t.) So, right off the bat, we know that Dr. Bridle is resurrecting old antivax misinformation and just applying it to COVID-19 vaccines.

Let’s look at his “concerns” about the study before I discuss the study itself, to see how the study is being spun:

I just finished reading a peer-reviewed scientific article that has been electronically published ahead of the print version. The findings have caused me considerable concern. The paper is entitled “Prenatal Exposure to COVID-19 mRNA Vaccine BNT162b2 Induces Autism-Like Behaviors in Male Neonatal Rats: Insights into WNT and BDNF Signaling Perturbations“.

Of course, the findings caused Dr. Bridle “considerable concern.” He’s antivax, which leads him to this statement:

Sadly, we should have had this comprehensive understanding and then conducted a fully informed risk-benefit analysis before hundreds of thousands of pregnant women were inoculated. But, maybe that is just my crazy way of thinking.

Funny how antivaxxers will seize upon a single study in rats as reason for incredible concern and ignore the clinical data that we have from huge numbers of people vaccinated during pregnancy whose sum total has failed to find evidence adverse maternal or fetal effects from vaccinating pregnant individuals with the COVID-19 vaccine but has produced a growing body of data demonstrates the safety of such use. (There’s even data that the vaccine administered during pregnancy might provide some immunity to the baby as well.) Yeah, a single rat study is going to overturn all that clinical data, because…reasons.

Yes, Dr. Bridle airily dismisses all the existing evidence thusly:

The published studies looking at this have largely been flawed and biased. Ever-emerging evidence proves that the harms of the shots have been substantially underestimated in all people. The only question is by how much? Worse, the studies done during pregnancy have focused most heavily on the women, and less so on the babies. In many cases, babies were followed for only a hand-full of weeks following their birth. This is much too short. And evaluations of these babies have been overly superficial. A classic trick when it comes to the research and development of novel medical interventions is this: one can make a product appear quite safe if one does not look very hard for harms.

Got that? That’s standard antivax conspiracy patter claiming that the only reason “They” don’t find vaccine harms is because “They” don’t look very hard. I swear, I can’t even remember the first time I heard that antivax trope because it was so long ago, nor can I remember the number of times I’ve heard the conspiracy theory that “They” are “suppressing evidence” of harms that antivaxxers so desperately want to attribute to vaccines.

Let’s look at the study now.

COVID-19 vaccines and autism…in rats?

The study in question was published a couple of weeks ago in a journal that I’ve never heard of before, Neurochemical Research, and entitled Prenatal Exposure to COVID-19 mRNA Vaccine BNT162b2 Induces Autism-Like Behaviors in Male Neonatal Rats: Insights into WNT and BDNF Signaling Perturbations. The journal itself, I found, has a respectable impact factor for a specialty journal (4.4.14 in 2023-4); so it’s not the typical crap journal that I usually see these sorts of studies in. It’s also garnered an Altmetric score of 2,827 as of this weekend, which is very high, in the 99th percentile, and has been accessed 56K times. As for the investigators, I am not familiar with any of them, but they are Turkish and come from Izmir Katip Celebi University, Istinye University, Afyon Kocatepe University, and Demiroğlu Bilim University, and the first (and corresponding author) is someone named Mumin Alper Erdogan, who last October also published a study in Journal of Neuroimmune Pharmacology entitled Prenatal SARS-CoV-2 Spike Protein Exposure Induces Autism-Like Neurobehavioral Changes in Male Neonatal Rats.

This latter study is different in that Erdogan injected pregnant rats with either saline, large amount of aluminum hydroxide adjuvant (150 μg/kg, which is within the range commonly recommended for preclinical rodent models), or a large amounts of spike protein (40 μg/kg!) plus a large amount of aluminum adjuvant and then tested the litters of mice for various behavioral traits used as models of autistic behavior, as well as immune markers thought to be associated with autism. Again, I was struck at how large the dose of spike protein was, microgram quantities in rodents that only weighed around 220 g, compared to the typical 70,000 g adult male human. This study was sold as indicating that COVID-19 infection during pregnancy could increase the risk of autism in the offspring of the pregnancy, finding:

At P50, we conducted behavioral analyses on these mature animals and performed MR spectroscopy. Subsequently, all animals were sacrificed, and their brains were subject to biochemical and histological analysis. Our findings indicate that male rats exposed to the spike protein displayed a higher rate of impaired performance on behavioral studies, including the three-chamber social test, passive avoidance learning analysis, open field test, rotarod test, and novelty-induced cultivation behavior, indicative of autistic symptoms. Exposure to the spike protein (male) induced gliosis and neuronal cell death in the CA1-CA3 regions of the hippocampus and cerebellum. The spike protein-exposed male rats exhibited significantly greater levels of malondialdehyde (MDA), tumor necrosis factor alpha (TNF-α), interleukin-17 (IL-17), nuclear factor kappa B (NF-κB), and lactate and lower levels of brain-derived neurotrophic factor (BDNF) than the control group. Our study suggests a potential association between prenatal exposure to COVID-19 spike protein and neurodevelopmental problems, such as ASD. These findings highlight the importance of further research into the potential effects of the COVID-19 virus on embryonic and fetal development and the potential long-term consequences for neurodevelopment.

My first question, of course, was why there was no spike protein alone group, because such a group would help figure out whether the immune system needed to be more stimulated, as with an adjuvant, for this effect to be observed. Still, my eyebrow was raised when I read this passage:

In light of the growing body of research indicating a connection between SARS-CoV-2 infection and neurological symptoms, we conducted a study to examine the potential impact of a synthetic version of the SARS-CoV-2 spike protein on the development of autism spectrum disorder (ASD) in offspring born to mothers exposed to the protein during pregnancy.

And, later:

In light of the growing body of research indicating a connection between SARS-CoV-2 infection and neurological symptoms, we conducted a study to examine the potential impact of a synthetic version of the SARS-CoV-2 spike protein on the development of autism spectrum disorder (ASD) in offspring born to mothers exposed to the protein during pregnancy.

Why the synthetic version? Why not compare to viral infection itself? Why such huge doses? Maybe I’m overly suspicious, but I get the feeling that this study was done in order to lay the groundwork for doing the study being promoted by Dr. Bridle that purports to show a link between the vaccine and autism after prenatal exposure to the vaccine. However, I’ll just take the Erdogan and the authors at their word for the moment that their intent was to study the neuroinflammatory effects of spike protein from infection as a potential promoter of neurodevelopmental disorders like autism spectrum disorders. The reason? Motivation doesn’t matter. Results do. Also, relevance matters, and these studies, as you will see, are not particularly relevant to the questions to which Dr. Bridle thinks they are very relevant.

Let’s move on to the study that so “concerns” Dr. Bridle, who opines later in his post:

I have two boys, so I became very familiar with babies a bunch of years ago. Let’s face it, the bulk of a baby’s early life consists of crying, drinking/eating, pooping/peeing, and sleeping. There is simply not a lot to evaluate when it comes to harms to babies that would manifest as behavioural issues. It is not unusual for babies to seem unhappy and uncomfortable on a regular basis. In other words, one cannot be confident in declaring an absence of a disorder in newborns and even toddlers. For example, I have heard that failing to make eye contact can be a potential sign of autism in young children. Obviously, such an observation cannot be made in a baby; they don’t start making consistent and intentional eye contact for quite some time. So, be very careful when you hear people declaring that there is no evidence of harm to children born to mothers that received the COVID-19 shots. There simply has not been enough time to properly evaluate this.

I like to point out that signs of ASD are often detected in children less than two and can be detected in infants as young as age 6-12 months, sometimes even as young as 3 months. When it comes to ASDs, Dr. Bridle simply doesn’t know what he is talking about here. There is even evidence that signs of autism can be detected in utero as early as mid-gestation. A little humility is in order here. For instance, I know that I am not an expert in neuroscience, autism, or neurodevelopment. I do, however, know from my many years combatting antivaccine misinformation claiming that vaccines cause autism that the signs of autism are detectable much earlier than antivaxxers commonly argue.

Not that that stops Dr. Bridle:

If COVID-19 shots administered to pregnant women can cause neurological harms in their developing babies, including alterations that lead to things like autism, it is almost certain that these could not be identified within the first six weeks. Humans need to gain certain abilities to interact with the world around them before health care professionals can properly assess for evidence of complex disorders. My goodness, some harms aren’t noticed until adolescence if hormonal changes are required to unveil them. This means there is the potential for harms to babies born to mothers that were coerced into getting the COVID-19 shots that we are still unaware of.

No one ever said that we could evaluate in a mere six weeks whether COVID-19 vaccines affect pregnancy outcomes. Again, though, he doesn’t know what he’s talking about here. You don’t have to wait until adolescence to see the signs of ASDs! Again, in some cases, the signs of ASDs can be detected in infancy. His entire argument is just an excuse to invoke the “no long term safety studies” gambit beloved by antivaxxers.

Let’s get to the study, though.

It’s a fairly straightforward study design, although not necessarily a straightforward study. Erdogan’s justification is:

While the mRNA vaccines have exhibited exceptional efficacy in forestalling severe COVID-19 manifestations and curtailing viral transmission, it is of paramount importance to scrupulously investigate the potential neurological ramifications associated with the spike protein itself and with the immune response it induces [1617]. Gaining a comprehensive understanding of the implications of spike protein-induced neuroinflammation, along with its impact on synaptic plasticity and overall brain development, will bolster our knowledge of the long-term effects of COVID-19 infection and its vaccination [18].

In this study, our primary objective is to delve deeply into the existing literature and data concerning the potential relationship between COVID-19 mRNA vaccines, spike protein-mediated reactions, and the genesis of neurodevelopmental disorders, focusing on autism. 


Through a detailed analysis of these carefully selected parameters, we aim to provide a clearer picture of this pressing area of research and offer directions for subsequent investigations [1920].

Is it that pressing a direction of research, though? Is it really? Current clinical evidence in hundreds of thousands, if not millions, of pregnant humans and their offspring have not raised a safety signal of neurodevelopmental disorders linked to the vaccine.

Dr. Bridle cites a reference indicating that many cases of ASD are not diagnosed before the age of 3 and some are not diagnosed until age 5, which is true enough, but not entirely relevant, not that that stops Dr. Bridle:

Here is the problem: Children born to mothers that were coerced into taking COVID-19 shots have not yet reached the age of three. We must now wait another 1.5 years, at least, and likely two or more years to accrue data from enough children to determine whether harms have been caused.

Yes, but there are a lot of children born to those vaccinated against COVID-19 during pregnancy who are getting quite close to 3 years of age, and, again, there are even more who are two years old and still more who are 12 months old. There’s nothing magic about being three years old. It’s more like an average. Lots of children are diagnosed earlier than that, and lots are diagnosed later than that. Although it is still early, with COVID-19 vaccines having only been authorized during pregnancy less than three years ago US, it’s not so early that safety signals for neurodevelopmental disorders in children born after having been exposed to the vaccine in utero through vaccination during pregnancy would not be starting to appear. It’s also a shame, because Erdogan has also published some interesting work in areas in which I’m interested, such as the role of ion channels in cancer. (I wonder if I met him in London in 2015, when I gave a talk at a conference on that topic.)

So how was the study carried out? In brief:

Two cohorts of female rats were randomly assigned to the following treatment groups: Group 1 or the 0.9% NaCl Saline Group (n = 7) and Group 2 or the COVID-19 m-RNA Vaccine BNT162b2 Group (n = 8). Throughout the experiment, the behavior and physical well-being of all animals were meticulously monitored daily. To facilitate the mating process, three female rats were cohabitated with a single male rat for a period spanning two to three days during the estrus phase. The presence of white vaginal plaque in the female rats was used as an indicator of successful mating. After this occurred, the male rats were removed from the enclosures.

After the mating, the rats were then treated thusly:

Rats belonging to Group 1 were administered 1 ml/kg of 0.9% NaCl saline intramuscularly on the thirteenth day of gestation. Simultaneously, rats in Group 2 received a dosage of 30 µg/Rat of the COVID-19 m-RNA Vaccine BNT162b2 intramuscularly on the same day of pregnancy. 

Let me first note that this is the full human dose of the Pfizer vaccine administered to rats whose average weight was only 220 ± 10 g. I realize that most people outside of the US are familiar with metric, but for nonscientists understand in the US I’ll just say that this is the equivalent of ~7.8 oz, less than half a pound. I’ll also note that even Dr. Bridle was forced to recognize this problem and try to handwave it away:

Pregnant rats received the same dose as what is given to pregnant women. Some will try to argue that this represents, on a per body weight basis, a higher effective dose. It might, but we don’t have proof of this. How drugs work can vary across species. There are examples where tiny rodents like mice could tolerate doses of drugs that were toxic in people.

Of course, that argument goes both ways, too. Many are the effects seen in rodent models due to drugs or other toxins that do not translate to people, although that doesn’t stop Dr. Bridle from arguing:

This research was conducted in rats. Pre-clinical studies like these are used to predict what might happen in humans. Sometimes the predictions are close. Sometimes the phenomena do not translate into people at all. And sometimes things are worse in people.

He also tries to hand wave why things might be worse in people:

The authors assume that much of the toxicity to the rats is mediated by the spike protein that the modRNA shots get cells in the body to manufacture. However, what they fail to acknowledge is that rats express the low-affinity receptor for the spike protein, unlike humans that express the high-affinity receptor. This means that the spike can only bind weakly to rat cells, but strongly to human cells. As such, I suspect that most of the harm observed in the rats might have been due to inflammation mediated by the lipid nanoparticles and/or immune responses against the spike proteins. If the spike proteins could contribute to the toxicity, then matters could be much worse in hosts with cells expressing high-affinity receptors, which would include people.

This is what we in the biz like to call JAQing off, “just asking questions” designed to lead the listener towards, in this case, the antivax viewpoint being promoted on Dr. Bridle’s Substack posts that the COVID-19 mRNA vaccines are dangerous during pregnancy (actually, that they’re just plain dangerous, regardless of pregnancy status, gender, race, age, etc.).

To continue in that theme, Dr. Bridle argues:

Further, the rats in this study were given a single dose, whereas pregnant women can receive up to two doses. The only way to know for sure is, unfortunately, to wait and see how the global human experiment pans out.

We’re already seeing that. The vaccines are safe and effective, albeit, thanks to mutation and the arrival of the Delta, Omicron, etc. variants and their ability to escape immunity from infection or vaccination against prior variants, they are less effective than they were three years ago.

Getting back to the study again, I note that there was no significant difference between the number of offspring per litter and no neonatal deaths among the litters in either group. Beginning on day 50 after birth (reset to day 1 for purposes of when the tests were administered), the rats born to Group 1 (controls) and Group 2 (vaccinated) were subjected to a number of behavioral tests:

Open Field Test: This initial assessment took place on Day 1. Serving as both a measure of general locomotor activity and anxiety, it also acclimated the rats to a testing environment. Novelty-Induced Rearing Behavior: On Day 4, the rats were evaluated for their vertical explorative behaviors in a novel setting. Three-chamber Sociability and Social Novelty Test: Administered on Day 7, this assessment provided insights into the rats’ sociability and their preference for social novelty. Their prior acclimation to the testing conditions by this point ensured accurate insights. Rotarod Test: On Day 10, the rats underwent this test to evaluate their motor skills and endurance. This physically demanding test was placed last in the sequence to minimize any fatigue or stress impacts on the outcomes of the earlier behavioral assessments.

One thing I noticed right away is something I frequently notice basic scientists failing to do when evaluating the results of rodent experiments, namely doing their observations under double-blind conditions, such that the evaluators do not know which group each rat being tested comes from. They state that they used an “artificial intelligence-based behaviour analysis system and software,” but the link to the system didn’t go anywhere yesterday. One can argue that some of the tests, such as the three-chamber test in which the rat decides between a chamber with no other rat and a “stranger” rat or between a chamber with a known rat and a “stranger” rat in which the test subject’s inclinations to be with one or the other are measured, don’t necessarily need to be double-blinded, but I will argue that all immunohistochemistry tests need to be double blind, even if a computer-aided counting system is used. The reason is that there is some subjectivity in all immunohistochemistry, and, in this case:

Systematic random sampling was employed to maintain uniformity across sections and minimize sampling bias. Counting was facilitated by an image analysis system (Image-Pro Express 1.4.5, Media Cybernetics, Inc., USA) to ensure accuracy and consistency. To ensure objectivity, neuronal counts were independently verified by two trained observers, with any discrepancies discussed and resolved to achieve a consensus count.

See why I think double-blinding would have been nice here?

In addition, several cytokines and immune system factors were measured by PCR from tissue harvested from the hippocampus of the rat brains.

In any event, key findings of the study included:

  • Differences in WNT gene expression and brain-derived neurotrophic factor (BDNF) in vaccinated rats, both male and female.
  • A substantial decrease in neuronal counts in critical brain regions, indicating potential neurodegeneration or altered neurodevelopment
  • Male rats reportedly demonstrated “pronounced autism-like behaviors, characterized by a marked reduction in social interaction and repetitive patterns of behavior.”
  • Male rats also demonstrated impaired motor performance, evidenced by reduced coordination and agility.

Here’s Table 4, showing some of the difference:

SexMale GroupsFemale Groups
Groups% 0.9 NaCl Saline Male GroupCOVID-19 m-RNA Vaccine BNT162b2 Male Group% 0.9 NaCl Saline Female GroupCOVID-19 m-RNA Vaccine BNT162b2 Female Group
Brain IL-17 level (pg/mg protein)109.7 ± 6.9112.09 ± 3.8128.6 ± 4.5118.9 ± 3.8
Brain BDNF level (pg/mg protein)806.8 ± 33.4680.7 ± 27.6 #773.6 ± 25.4628.9 ± 24.9 *
Brain TNF-alpha level (pg/mg protein)94.6 ± 0.392.09 ± 4.4111.3 ± 4.1104.3 ± 4.5
Brain IL-1 level (pg/mg protein)22.7 ± 1.0119.6 ± 0.522.7 ± 0.421.9 ± 0.9
  1. Results were presented as mean ± SEM. Statistical analyses were performed by one-way ANOVA. # p < 0.001, different from % 0.9 NaCl Saline Male Group and * p < 0.001, different from % 0.9 NaCl Saline Female Group. For male rats, a significant decrease in brain BDNF levels was evident in the vaccinated group (F(1, 36) = 10.24, p < 0.001), suggesting a specific impact of the vaccine on neurotrophic factors. Similarly, for female rats, brain BDNF levels were significantly lower in the vaccinated group as compared to controls (F(1, 36) = 11.67, p < 0.001), reinforcing the potential influence of the vaccine on neurotrophic signaling

I am familiar with the role of WNT signaling (a molecular pathway that transmits extracellular signals to the nucleus to turn on and off sets of genes that modulate its effect) in cancer, but less so in the brain. The simple version is that WNT signaling is important in neurodevelopment and that impaired WNT signaling can result in various neural impairments, and some research implicates it in the development of ASDs. As for BDNF, it too is important in neurodevelopment, and there is research implicating abnormalities in BDNF signaling with ASDs.

Also, there was noted to be a difference in neuron counts in the hippocampus:

SexMale GroupsFemale Groups
Groups% 0.9 NaCl Saline Male GroupCOVID-19 m-RNA Vaccine BNT162b2 Male Group% 0.9 NaCl Saline Female GroupCOVID-19 m-RNA Vaccine BNT162b2 Female Group
Neuronal Count CA171.8 ± 3.554.5 ± 1.3 #68.5 ± 1.966.1 ± 0.8
Neuronal Count CA343.6 ± 1.730.2 ± 1.1 #42.2 ± 1.339.1 ± 1.1
Purkinje Count Cerebellum21.9 ± 1.413.5 ± 0.9 #19.8 ± 0.618.3 ± 0.9
  1. Results were presented as mean ± SEM. Statistical analyses were performed by one-way ANOVA. # p < 0.001, different from % 0.9 NaCl Saline Male Group. For the male groups, significant decreases in neuronal counts were observed in the CA1 (F(1, 36) = 23.45, p < 0.001), CA3 (F(1, 36) = 28.37, p < 0.001), and Purkinje cell count in the cerebellum (F(1, 36) = 34.12, p < 0.001) regions, indicating a robust effect of the vaccine. Conversely, the female groups did not show significant differences between treated and control groups in the CA1 (F(1, 36) = 3.21, p = 0.081), CA3 (F(1, 36) = 4.78, p = 0.034), and Purkinje cell count in the cerebellum (F(1, 36) = 5.52, p = 0.024)

Let’s for a moment just accept these results as accurate, the way Dr. Bridle did. Let’s say that the findings of differences in cytokine profiles and neuronal counts between the offspring of vaccinated and unvaccinated rats, , as well as the behavioral differences observed, were accurately measured. What does this mean?

Before I answer that question, I can’t help but mention that I’m glad actually perused the references cited in the study and came across this reference, buried among multiple citations to support a claim:

Bridle cites an article that cites Seneff.
Erdogan cited Stephanie Seneff and Peter McCullough? Uh-oh. Maybe I was too kind…

Yikes. And uh-oh…again:

Bridle cites an article that cites Seneff
No wonder Dr. Bridle likes this study. The authors have cited two of the worst antivax papers I’ve ever seen about COVID-19 vaccines whose authors include one of the worst “new school” antivaxxers (McCullough) and one of the worst “old school” antivaxxers (Seneff).

I take back what I said above when I questioned whether I was being too suspicious of this paper. When you cite two Stephanie Seneff papers, you deserve the suspicion that I had, and it isn’t surprising to me that Dr. Bridle likes this paper. If anything, I was probably not suspicious enough about Erdogan, particularly given the conclusion made by him and his coauthors:

Given the public health significance of understanding the effects of COVID-19 vaccination, especially during pregnancy, comprehensive studies are vital. These should weigh the benefits and potential risks of vaccination, focusing on ensuring optimal neurodevelopmental outcomes. Our findings underscore the importance of continued research in this domain to guarantee the safety and well-being of all individuals, especially those who are pregnant and their offspring.

In summary, this study provides valuable insights into the effects of the COVID-19 mRNA BNT162b2 vaccine on the WNT pathway and BDNF levels, particularly in relation to neurodevelopmental outcomes. The observed male-specific vulnerability and the convergence with existing literature support the involvement of these molecular pathways in neurodevelopmental disorders. However, further research is warranted to validate these findings in human populations and to unravel the complex mechanisms underlying the observed effects. The ultimate goal is to ensure the safety and well-being of individuals receiving COVID-19 vaccination, particularly during pregnancy, while minimizing potential risks to neurodevelopment.

More of a favorite antivax gambit, namely “we need more research.” It’s a gambit used no matter how massive the evidence base against an antivax claim is, such as the old claim that vaccines cause autism.

I deconstructed in depth that paper on G-quadruplexes nearly two years ago! As for the paper on “human genome integration,” I didn’t discuss that paper in particular, but did discuss many times how the claims that the mRNA vaccine can “integrate” into the genome is nonsense. No wonder Dr. Bridle and other antivaxxers like this study!

Relevance, ignored by antivaxxers like Dr. Bridle

The question one has to ask when confronted with a study like this is one of relevance to humans. Even Dr. Bridle recognizes this issue, as he spends considerable verbiage trying to dismiss criticisms based on whether this study is even relevant to what happens in humans while JAQing off in order to make you think that we must treat the results as relevant even though there are a lot of reasons not to, as well as a large amount of data from epidemiological studies of the use of COVID-19 vaccines during pregnancy.

Enter the pandemic’s wrongest man, Alex Berenson, echoing Dr. Bridle’s nonsense about this study:

Naturally, like Dr. Bridle, Mr. Berenson trumpeted this on his Substack in an article entitled URGENT: Giving mRNA Covid vaccines to pregnant rats caused brain changes and autism-like behavior in their young, a new study shows, with the conspiratorial tagline: Naturally, the disturbing finding – which was published in a respected, peer-reviewed journal last week – didn’t come from American scientists and a sarcastic conspiratorial comment in his post:

(Luckily Pfizer did a ton of work to make sure this wouldn’t be problem in humans. Oh, they didn’t? Hey, everyone makes mistakes.)

Again, it’s all about the fear and doubt about the vaccines and ignoring all the human evidence out there:

The study coved only about 40 rats, and it does not prove the vaccines cause autism or similar brain changes in the children of vaccinated pregnant women.

But it does show – again – that the jabs can cause powerful inflammatory and autoimmune responses with unknown consequences, and that their long-term risks have barely been studied.

Mr. Berenson is also ready with an excuse that antivaxxers have been making for two decades:

But neither governments nor vaccine companies have shown any inclination to do that work. And so even if autism diagnoses notably rise in the next few years, proving the mRNAs are responsible will be next to impossible.

Actually, it would be quite possible, in the very same way that doctors studied the vaccine schedule and tried to correlate it with autism diagnoses for the last 30 years and have failed to find a link. It’s just that antivaxxers won’t accept those results. They didn’t accept them for the childhood vaccine schedule, and they won’t accept them for COVID-19 vaccines.

Again, Mr. Berenson is JAQing off, just like Dr. Bridle. Again, it is very much unclear how relevant a model can be in which a dose of vaccine relative to animal body weight so much larger than what is administered to humans and the physiology of pregnancy is so different. One can also question how relevant the behavioral models are to human autism. For example, the three-chamber test has a definite drawback:

To test a mouse’s social interest, researchers place it in a cage that has two side chambers, one of which holds another mouse. Mice normally prefer to investigate the mouse rather than spend time in the empty space. Some of the autism mouse models spend as much or more time in the empty cage, which researchers take to be an indication of social deficits.

But this test relies on an artificial scenario, in which the new mouse is caged and cannot initiate social contact, says Paylor. Tellingly, the FMR1 and NLGN3 rat models both ignore social play, but act normally in the three-chamber test.

“Having a barrier between animals may completely alter the way animals normally interact, and certainly in young rats it prevents rough-and-tumble play behavior,” says Paylor. 

I also note that the rats in the Erdogan study were not pups. They were 50 days old and had reached maturity, which is rather late to have been studying the rats. Indeed, one could question why the behavioral part of the study was even designed the way it was when there are rat models that can examine behaviors more relevant to ASDs. I get it. The three-chamber model used is fairly simple and straightforward, but it’s not particularly relevant, particularly not with mature rats.

I could go on and on and on, but I think one of the most telling things I noticed was the reappearance in the comments of Mr. Berenson’s post of an old “friend,” J.B. Handley, founder of Generation Rescue and old school “mercury in vaccines causes autism” leader who’s been fairly quiet for quite a few years. Amusingly, he’s annoyed at Mr. Berenson for previously not having been willing to consider this:

Alex: Your unwillingness, to date, to consider the childhood vaccine schedule’s role in the autism epidemic has been very frustrating for people like me who otherwise conisder you a hero. I hope this revalation helps you re-consider that somehow, magically, the childhood vaccines cause no problems…If you are looking for a mechanism of action, Cal Tech’s Paul Patterson proposed a very clear one more than a decade ago: immune activation events in the brains of babies during critical periods of brain formation. These simmering brain infections can be caused my many different antagonists, but man-made nanoparticle aluminum (the kind found in vaccines that isn’t found in nature) is an obvious culprit, becuase lymphocytes transport it to the brain and the body cant excrete it. There’s likely something similar happening with the mRNA shots that hit the brains of the baby rats, perhaps it’s the spike protein.

I was amused. Mr. Berenson is not sufficiently antivax for old-school antivaxxers, although apparently Dr. Bridle is.

As I wrote at the beginning this post, there is nothing new under the antivax sun. Every antivax claim made about COVID-19 vaccines has a precursor from the beforetime. Also, as I said above, it is nearly inevitable that “new school” antivaxxers who became antivax because of COVID-19 vaccines will over time become become just antivax. As it becomes clear that there is no increased risk of neurodevelopmental disorders like ASDs in children born to individuals vaccinated during pregnancy, the focus will shift (is likely already shifting) to blaming COVID-19 vaccines given to 6 month olds for autism. Same as it ever was.

By Orac

Orac is the nom de blog of a humble surgeon/scientist who has an ego just big enough to delude himself that someone, somewhere might actually give a rodent's posterior about his copious verbal meanderings, but just barely small enough to admit to himself that few probably will. That surgeon is otherwise known as David Gorski.

That this particular surgeon has chosen his nom de blog based on a rather cranky and arrogant computer shaped like a clear box of blinking lights that he originally encountered when he became a fan of a 35 year old British SF television show whose special effects were renowned for their BBC/Doctor Who-style low budget look, but whose stories nonetheless resulted in some of the best, most innovative science fiction ever televised, should tell you nearly all that you need to know about Orac. (That, and the length of the preceding sentence.)

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10 replies on “Will COVID-19 vaccines drive an “epidemic of autism”? No, but Byram Bridle thinks so.”

I rather suspect that he does have tenure, because on his Substack near the top I find this statement:

It has been two years, six months, and five days (917 total days) since the administration of my employer, the University of Guelph, banned me from accessing my office and laboratory. I spoke truths about COVID-19 when much of the world was not ready to hear them. As I am still expected to work, I would like to have access to my work spaces. Segregation makes me feel less than human.

Why would the the University of Guelph do something like this instead of firing Dr. Bridle outright? My guess is that it’s because he has tenure and the university can’t outright fire him.

A. Reminder: there is a recent study in human babies looking at this question.

It found no such issue. This is quoting from the abstract, but it does reflect the findings: “In this cohort study including 2261 and 1940 infants aged 12 and 18 months, respectively, in utero exposure to COVID-19 vaccination was not associated with abnormal neurodevelopmental scores on the Ages and Stages Questionnaire, third edition, at 12 or 18 months of life.

Meaning Results suggest that maternal vaccination against COVID-19 during pregnancy was safe from the perspective of offspring neurodevelopment up to age 18 months.”

B. We did consider risks. That is why initially pregnant women were not advised to vaccinate. The recommendation changed as the risks of covid-19 in pregnancy became more obvious.

These risks do not seem to bother these people.

That same study found a 25% greater relative risk of neurodevelopmental disorders in children born to mothers vaccinated in the first trimester, compared to mothers vaccinated in the third trimester. (page 2 of the Supplement)

Why would such a relationship be the case if the vaccine did not affect neurodevelopmental disorders? Just curious


No. It found no such thing. What it found was:

We observed more abnormal screens for developmental delay among male vs female infants at 12 and 18 months of age overall, without regard to exposure status (12 months: 325 of 980 [33.2%] vs 278 of 984 [28.3%]; χ2 = 5.57; P = .02; 18 months: 210 of 872 [24.1%] vs 161 of 836 [19.3%]; χ2 = 5.84; P = .02). On calculating stratified estimates by sex from a model including interactions between sex, exposure, and age, at 12 months of age, we observed an increased risk of delay among exposed male infants in the unadjusted and adjusted analyses in model 3 (aRR, 1.29; 95% CI, 1.04-1.62) (Table 3)—a difference that was not sustained at 18 months (aRR, 1.06; 95% CI, 0.80-1.41) (Table 3). Meanwhile, a divergent pattern was observed for female infants. At age 12 months, there was no difference in risk of abnormal ASQ-3 screen among exposed vs unexposed (model 3 aRR, 1.02; 95% CI, 0.81-1.30) (Table 3); however, a reduction in risk was observed among exposed female infants at age 18 months (model 3 aRR, 0.69; 95% CI, 0.51-0.93) (Table 3).

In other words, the finding in males wasn’t sustained. Also, if you’re going to believe that the finding in males was real and caused by the vaccine you have to believe that the protective effect (which you don’t mention in your blog) in females must also be real. So by your interpretation of this study, vaccination must be protective against neurodevelopmental disorders in females.

As for the supplemental data:

Supplemental analyses exploring trimester of vaccine were conducted. Among individuals vaccinated during, 574 of 1674 (34.3%) were vaccinated in the first trimester, 751 of 1674 (44.7%) in the second, and 349 of 1674 (20.9%) in the third. There was no difference in prevalence of abnormal screen for developmental delay based on trimester of exposure at either 12 or 18 months. Abnormal 12-month screen for first, second, or third trimester vaccination exposure was 32.5% (170 of 523), 30.7% (212 of 690), and 26.1% (82 of 314), respectively (χ2 = 3.86; P = .15). The corresponding figures at 18 months were 20.7% (92 of 444), 21.2% (120 of 567), and 17.5% (48 of 274), respectively (χ2 = 1.62; P = .45). Null findings were sustained in all models (eTable in Supplement 1), with an exception of a signal for reduced developmental delay risk at 18 months after third trimester vaccination in the partially adjusted but not fully adjusted models (aRR, 0.72; 95% CI, 0.52-1.00 and aRR, 0.78; 95% CI, 0.56-1.09, respectively) (eTable in Supplement 1).

In other words, no, there was no statistically significant finding here, as the authors noted:

We observed differential outcomes of exposure on neurodevelopmental delay by sex. Maternal COVID-19 vaccination was associated with increased risk of abnormal ASQ-3 screen at 12 months in male infants but not at 18 months. Interestingly, an electronic heath record study from 2 prominent Massachusetts health systems examining International Statistical Classification of Diseases and Related Health Problems, Tenth Revision, billing codes for neurodevelopmental disorders identified an increased risk for neurodevelopmental disorders at 12 months among male but not female infants after in utero exposure to COVID-19 infection; this association was similarly not sustained at 18 months.27 It is unclear whether these findings, in conjunction with those of our study, are spurious or associated with a true but transient phenomenon linking inflammatory exposures to developmental trajectories.

Most likely it’s a spurious finding.

Seriously, Igor, you are in way over your head.

A very interesting in-depth look at the study that was discussed by many people!

When I saw the descriptions of “sociability test”, “social novelty test”, and the “motor skills Rotarod test”, I thought, geez, I would fail all three. I would fall off the Rotarod faster than any of those rodents. (I have plenty of neurons, though. On some days those neurons work better and on some days, worse.)

Anyway, most substances that cause problems with fetal development have a limited “window” during pregnancy where they could cause malformations or problems described by Erdogan et al.

Usually the first trimester is riskier.

The COVID vaccine was approved by the FDA and the CDC for pregnancies in May of 2021. So the first-trimester pregnancies that were affected that could show ill effects would be pregnancies conceived around April 2021. Those babies were born in Jan 2022 and the surviving ones would be close to 2 years of age as of now. So we will see soon.

Why did I mention the first trimester? Another study by Jaswa et al., titled In Utero Exposure to Maternal COVID-19 Vaccination and Offspring Neurodevelopment at 12 and 18 Months, found that HUMAN infants born to mothers vaccinated with Covid vaccine during first trimester, did considerably worse that infants born to mothers vaccinated during second and third trimester.

According to the table on the second page of the Supplement, infants born to mothers vaccinated during the first trimester, have about 25% MORE developmental abnormalities than infants born to mothers vaccinated in third trimester (RR values).

Just as Erdogan’s rats, so, perhaps, Erdogan is onto something…

Again, that study showed no such thing. Again, Igor, you don’t know WTF you are talking about, nor do you understand how to interpret complicated clinical research like this. Moreover, the authors of the study discussed all these findings and noted:

On the other hand, we observed an associated reduction in risk for abnormal ASQ-3 screen among female infants exposed to COVID-19 vaccination in utero at 18 months, a result unchanged by the addition of maternal COVID-19 infection to the model. In the absence of biological plausibility for how exposure to vaccination may promote female neurodevelopment, we are left to consider the possibility of residual confounding.

In other words, the findings of worse ASQ-3 screens among males at 12 months was not sustained, and in females the vaccines appeared to be protective against this effect. The authors correctly point out that there is no biological mechanism or plausibility for this observed effect, which leaves the most likely explanation as some sort of residual confounding.

Seriously, Igor. It is very telling that you focused like a laser beam on that one table that showed what you wanted to see, apparent harm from COVID-19 vaccination during pregnancy, and ignored the effect that looks like vaccination during pregnancy protect female offspring against neurodevelopmental disorders. You can’t have it both ways. If you’re going to say that the results of this study are not the result of some sort of residual confounding, then you have to accept ALL its results, including the finding that vaccination during pregnancy is, according to this finding, beneficial to female offspring in terms of the risk of neurodevelopmental delay and disorders. But you don’t. You focus on the one result that you want to believe and ignore the one that you don’t.

Because you are an antivaxxer, and that’s what antivaxxers do.

It’s like “vaccines cause autism” is the tenet of a new religion. Despite all the evidence to the contrary, it has become orthodoxy.

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