What to know about vaccines in the do-your-own-research era
- For most of human history, the cause of disease was largely unknown, and infected patients had no robust medical interventions to help them combat the associated illnesses.
- Over time, science and medicine uncovered the underlying cause of disease: microscopic pathogens, as well as ways to treat and, most importantly, prevent them.
- The development of vaccines, widely adopted in the 20th century, brought an end to a large number of preventable diseases. They don’t have to come back here in the 21st century; that’s up to us.
The United States used to be a very different place not so long ago. When a new child was born and was first taken to the doctor, the doctor would talk the parents through a schedule of expected care for the first few months and years of the newborn’s life. That expected care included, importantly, a schedule for vaccines: a series of inoculations, given at pre-set times in a child’s development, that would protect them against diseases that had ravaged humanity for generations prior. This included protections against diseases such as:
- polio,
- smallpox,
- measles,
- rubella,
- mumps,
- diphtheria,
- pertussis (whooping cough),
- tetanus,
- hepatitis,
- typhoid,
- rabies,
- cholera,
- cervical cancer,
- bacterial meningitis,
as well as many more.
When a child is first born, their immune systems are very weak, and hence they are very susceptible to (and at risk of being killed or permanently disabled by) a variety of infectious diseases. Vaccines were the way to reduce both the risk of infection and the consequences of infection in all, including our most vulnerable (the very young, the elderly, and the immunocompromised), while simultaneously having a tremendous public health benefit. In fact, vaccines were rated the most effective public health measure of the 20th century by the Centers for Disease Control (CDC).
And yet, many are now confused by conflicting guidelines from government agencies and spokespeople, along with medical professionals, here in 2025. In the era of do-your-own-research, here are answers to nine major questions that a great many people, including parents, have today.
What do vaccines do?
Vaccines are medical interventions designed to strengthen a patient’s immune system against specific, vaccine-preventable diseases, with the goal of controlling, eliminating, or even eradicating those diseases and their spread in the human population. The way that “classical” human vaccines (i.e., all vaccines prior to the 1960s) work, in general, is that they take what’s known as an inactivated or attenuated infectious disease agent (i.e., bacterial or viral agent), which is a weakened, dead, or otherwise non-virulent pathogen, and exposes a human host to that non-dangerous agent. This produces an immune response in the vaccinated human, leading to a generally strong, effective, and long-lasting immunity.
The body both creates antibodies immediately and maintains a memory of that immunity, so that it can produce antibodies if ever it encounters that pathogen again: even if it’s a long time down the road. Vaccines can be administered in multiple ways, including:
- subcutaneously, or just underneath the skin,
- intradermally, or into the mid-layer of the body’s dermis,
- nasally, or through the nose,
- or orally, or through the mouth.
Most of the vaccines that are available today, including vaccines against measles, mumps, rubella, yellow fever, and varicella are live attenuated vaccines, although other types like inactivated vaccines and mRNA vaccines, are also now widely available.
Are there any unnatural or dangerous ingredients that are part of vaccines?
Vaccines normally only contain a very, very small amount of “active ingredients,” which are the components of the vaccine that are made from viruses or bacteria. (These components are sometimes known as antigens.) A typical vaccine only has micrograms worth of these active ingredients, and these are the key parts that stimulate the needed immune response.
There are also inactive ingredients that perform two major functions:
- to improve the immune response to the vaccine, such as aluminum salts and MF59, which are known generally as adjuvants,
- and to stabilize and preserve the vaccine, such as sugars, sorbitol (in the chickenpox vaccine), gelatine, egg albumin, and thimerosal.
None of these ingredients are unsafe, except in the rare case where the human receiving the vaccine has an allergy to the specific ingredient used. (For example, an egg allergy, a sorbitol allergy, or a lactose allergy. If you have these, or any other relevant, allergies, you must let any and all vaccine providers know about them!) Thimerosal contains mercury and, although it has been the subject of many discussions and was removed from all vaccines more than a decade ago, is not dangerous to humans in any way. Although many of the ingredients found in vaccines are not “natural” in the sense that they are synthesized in a laboratory, they are fully safe.
What about all of the stories of vaccine injury that are out there?
There is a reporting center run by the CDC called the VAERS database: the Vaccine Adverse Event Reporting System. The database contains — and this is important here — unverified reports of illnesses, health problems, or symptoms following immunization. Reports are accepted from anyone who took a US-licensed vaccine and are never rejected, and have been collected from 1990 onward.
To be fair, there are a great many reports in the system: totaling in the hundreds of thousands. However, the CDC explicitly cautions (bold theirs):
“The number of reports alone cannot be interpreted as evidence of a causal association between a vaccine and an adverse event, or as evidence about the existence, severity, frequency, or rates of problems associated with vaccines.”
This is because humans have a baseline rate for getting ill, displaying symptoms, or experiencing health problems, independent of vaccines. If you (or your young child) started having an adverse health event 48 hours prior to receiving a vaccine, you would never attribute the event to the vaccine. However, if that same health event occurred 48 hours after receiving a vaccine, you, like many, might be quick to blame the vaccine, and to report any adverse health event to the VAERS database. When scientists consider the occurrence of adverse reports versus the baseline rate for health symptoms in general, there appears to be no link between them and vaccinations in general, save for two common and mild ones:
- pain around the injection site,
- and minor flu-like symptoms that last up to 24-48 hours.
While the reports may be real, they do not point to any risks or dangers associated with vaccination. More recently, a few rare effects were noted with a variety of COVID-19 vaccines, but even those effects only confirmed pre-established safety signals, including for myocarditis, pericarditis, Guillain-Barré syndrome, and cerebral venous sinus thrombosis.
Should I listen to my pediatrician/doctor about vaccines?
It depends. Back when the CDC represented the “gold standard” for public health (in my assessment, just prior to the appointments of Brenda Fitzgerald in 2017 and Robert Redfield in 2018 as the 17th and 18th directors of the CDC), I was listening to a good medical doctor (an evidence-based MD) who was responding to a patient who was hesitant about vaccines. The doctor spoke at length about:
- the CDC’s recommended vaccine schedule,
- alternative vaccine schedules promoted by certain doctors,
- the risks of vaccination and the risks of not vaccinating against preventable diseases,
and gave what sounded like a very reasonable summary of then-current thought on all of these issues.
And then the doctor said something I never would have expected, stating, “But, that’s just what I know and think about these issues, and I would in no way ever dare to presume that my knowledge is sufficient when compared to what the recommendations of the CDC are.” The doctor then went on to state how many thousands of scientists studied explicitly all of the issues associated with vaccines and vaccinations as part of the CDC, and how grossly underqualified any individual doctor, even an evidence-based MD, is in comparison to the cumulative knowledge and expertise possessed by the scientists who work at the CDC.
I would say that if your pediatrician/doctor doesn’t agree with the vast majority of what the CDC (explicitly excluding the current administration) has concluded concerning vaccines, including their most up-to-date immunization schedules as of late-2024, then no, you should not listen to them. That should, honestly, be your giant red flag to go and find a better, more evidence-based doctor.
If I don’t vaccinate my child or my family, how does that affect others?
This is a hugely underappreciated aspect of vaccines: the effects it has not only on others, but on the infectious diseases that humans are attempting to protect ourselves against. It comes from the confluence of a number of facts.
- For everyone who receives a vaccine, there is a small but non-negligible percentage of recipients who will not develop a very effective immunity against that vaccine. For measles, for example, it’s about a ~3% rate.
- There is a very vulnerable population of people who cannot receive vaccines, including the immunocompromised, extremely ill, and those who are too young to receive certain vaccines.
- And that when someone is infected with a disease (or, worse, multiple diseases at once), there’s the potential for that disease to mutate (or, in the case of multiple simultaneous infections, to experience horizontal gene transfer), creating the possibility that a new, more infectious, more virulent disease, including one that evades vaccine immunity, can arise.
Many vaccine-preventable diseases, such as measles, have extremely high infection rates. Unless ~95% of the populace has immunity to such a disease (most commonly acquired through vaccination), infections will lead to outbreaks, epidemics, or even pandemics. Lots of infections mean many deaths and new permanent disabilities, and also the potential for the emergence of a new strain or an entirely new “chimera” disease, that could potentially be even worse than anything presently known. If you don’t vaccinate your child or your family, you are personally contributing to these risks: to your child, your family, to newborns, to the elderly, to the ill, and to humans on planet Earth.
What are the differences between modern mRNA vaccines and older non-mRNA vaccines?
Traditionally, as stated earlier, non-mRNA vaccines use either an inactivated or a weakened germ/pathogen which then enters into our bodies, whereupon our bodies recognize them as a foreign agent and this triggers an immune response in us, which eventually leads to protection from the vaccine.
What mRNA vaccines do, instead, is they use a specially created strand of messenger RNA (mRNA) that, when it enters our bodies, teaches our cells to make either a whole protein or a protein fragment. That protein (or protein fragment) then — even though our own bodies made it — gets recognized as a foreign agent, and this triggers an immune response in us: the same type of response that an inactivated or attenuated vaccine would trigger.
That’s it. That’s the big difference: instead of putting a foreign virus or bacterium into our bodies and saying, “go to town, immune system,” we’re putting a piece of genetic code into our bodies. Those pieces of genetic code (the mRNA) will then enter our muscle cells and take advantage of the cellular machinery we all already possess to make a protein or protein fragment, and upon seeing that protein, our immune system will “go to town” exactly as before. It’s just a different tool, more effective and successful for some infectious diseases than the traditional approach, that we have to confer immunity through vaccination.
In the specific case of the mRNA COVID-19 vaccines, this also helps us understand how they were able to get these vaccines out so quickly: the technique had already been developed, and it was just a matter of isolating the key features of the spike protein (and the mRNA sequence that encodes it) to create a SARS-CoV-2 specific vaccine. This technique is rapidly being applied to other diseases as well; many anticipate that mRNA vaccines will offer cures and/or preventative measures against many other pathogens in the coming years.
Why are there so many vaccines today compared to when I was a child?
There are more vaccines today than there were decades ago for two simple reasons.
- Diseases for which there were no vaccines now have vaccines against them, and so we have the ability to protect ourselves against infections, today, that we were unable to protect ourselves against previously. A good example is chickenpox, for which the first US-approved vaccine emerged in the mid-1990s, but for which older people (like me, who was born in 1978) had no vaccine against when we were young; infections were generally common and mild, but ~150 people per year died of a chickenpox infection. With vaccines available, those deaths can now be prevented entirely.
- Immunity can wane. There are several reasons for this, but the two most common are that your body “forgets” how to have the proper immune response over time, and that diseases mutate so that prior immunity no longer provides current immunity. The solution in both of those cases is to receive another vaccination: either a booster shot in the case of a non-mutating disease or a new vaccine against the current strain in the case of a mutating disease. This latter reason is why influenza and COVID-19 vaccines are constantly being updated, and why fast-mutating viruses, such as coronaviruses, are so good at evading prior immunities.
The TL;DR version: there are more vaccines now than there used to be because these additional vaccines confer better protection and more comprehensive protection against greater numbers and types of infections than the fewer vaccines we used to administer.
Shouldn’t there be double-blind, placebo-controlled vaccine trials?
This is something currently being pushed by the current head of the Department of Health and Human Services, and the answer is emphatically absolutely not, because it would be unethical to do so.
Allow me to explain.
Double-blind, placebo-controlled trials involve willfully exposing patients to the disease without also exposing them to the (potential) cure/prevention/treatment. This is useful in clinical trials with already-infected or already-afflicted populations, but the Hippocratic Oath of “do no harm” would be violated if you exposed someone to potential harm that they wouldn’t have been exposed to if they hadn’t been a part of your trial.
This goes all the way back to Joseph Lister: the pioneer of antiseptic surgery. Looking to test whether the theory of antisepsis was true or not, he began to engage in a practice where:
- he would either clean and sterilize the patient, the surgery site, the surgical tools, and the surgeon’s hands,
- or he wouldn’t perform that cleaning and sterilization.
He was only about 40 patients into that test run when he aborted the trial. In the “clean and sterile” group, about 10% of the patients wound up dying shortly after surgery. But in the “control” group, a full 50% of the patients had died. To continue the trial would have been unethical, and so instead of doing so, he simply started applying antisepsis techniques to everyone.
To date, there’s never been a full-scale study that’s compared antiseptic techniques using a double-blind, placebo-controlled trial, because it would be unethical. Similarly, there’s never been a double-blind, placebo-controlled trial about dental flossing, because it would be an unethical act of causing harm to the group of non-flossers. This doesn’t mean that antisepsis isn’t safe or effective; it doesn’t mean dental flossing isn’t safe or effective. It means that we have a better solution than a double-blind, placebo-controlled trial for making sound recommendations about those issues. The same is true for vaccines, and we should all understand this, especially in the light of recent political appointments that shove scientific merits to the sidelines.
Why have the rates of autism increased so significantly, if not for vaccines?
Despite the fact that the original “study” linking vaccines to autism was fraudulent and retracted, and despite the fact that much larger studies have shown that there is in fact no link between them at all, the myth persists among the general public. Autism rates are up, and children are getting more vaccines than ever, and many think there could be a link. This myth is not only wrong, but it’s a dangerous piece of misinformation, it has deadly consequences for the unvaccinated and all whom they infect, and it’s dehumanizing to the autistic members of our community and society.
Every time I hear about the vaccines-cause-autism idea, it makes me think of my deceased grandmother: Selma. She was a great cook, and I would “help” her in the kitchen as a kid, where my “help” usually consisted of doing things like “handing her a cucumber” or “putting black olives on my fingers” so that I wasn’t doing anything more disruptive. She made traditional foods that I didn’t get to eat anywhere else: blintzes, kreplach, and chicken noodle soup. But I also remember that she often had bandages on her fingers, and I remember one time where she cut herself (while cutting vegetables) so deeply that there was a debate over whether she needed to go to the hospital.
How could a woman who was such a great and experienced cook, and who was such a careful and deliberate person in practically all aspects of her life, wind up cutting herself so frequently?
Because when Selma was a schoolchild, she would get hit on the hand every time she would use her left hand to pick up a writing implement. The old tale of “being rapped with a ruler” was true: it happened to her until she learned, as everyone did in her school, to write with her right hand, not her left. As an adult, she always held the kitchen knife in her right hand, never her left. As her left-handed grandchild, I wondered how much better her life would’ve been if she was simply allowed to be who she naturally was: a left-handed person, instead of being behaviorally compelled to use her less dexterous right hand to perform her everyday activities. The observed rate of left-handedness has increased from a low of ~3-4% in the early 1900s to a steady rate of ~11-12% today. It isn’t because more people are naturally left-handed now; it’s because we have both stopped persecuting left-handed people and have more successfully identified who is, naturally, a left-handed individual.
The reason autism diagnoses have continued to rise is exactly why I think of my grandmother: because instead of only diagnosing a subset of autistic individuals, and instead of persecuting them, we’ve now recognized that:
- autism is a spectrum,
- that it isn’t a pathology but rather a natural subset of the human population,
- that it includes not just the profoundly autistic but mid-functioning and high-functioning autists, as well as those with Asperger’s,
- and that if you get a diagnosis of autism, you can better understand yourself and better find your way (and find a supportive set of communities) in this world.
Although many are looking at the “do-your-own-research” era as a big win for freedom, the truth is that the only freedom it gives us is the freedom from expertise, and the freedom to unknowingly harm ourselves and others while thinking, mistakenly, that we’re actually engaging in an act of protection. We should love, accept, and support the autistic people in our lives; we shouldn’t try to “fix” them or “cure” them. This is who they are, and it isn’t because they were vaccinated. Vaccines prevent infections and mitigate the harmful effects of breakthrough infections, and are the safest and most effective public health measure of the last century. If you scrupulously do your own research, you’ll find the exact same thing out for yourself.
Ethan Siegel, the author of this piece, is not a medical professional and none of these recommendations should be construed as medical advice. These questions and answers are for informational purposes only, and all medical decisions should be made with the help of a qualified, evidence-based MD or DO.
