Multiple vaccinations weakens the immune system – a myth

If you explore the dark and myth filled back alleys of the antivaccination movement, you will find a wide variety of myths that try to convince people that vaccinating children is dangerous. I’ve covered and refuted many of the myths, although the vaccine deniers tend to rely on zombie myths that keep returning over and over again, never quite dying.

These myths range from outrageous, such as it’s a conspiracy of the government to control population (which I find odd, since the government is barely competent enough to build a post office), to scientific sounding, but ultimately pseudoscientific claims. There are a lot of great websites that debunk many of the myths, and they’re easy to find.

One of the most annoying legends of the antivaccination cult is that multiple vaccinations weakens the immune system of the poor baby’s tender physiology. About that immune system? It’s comparatively strong relative to almost every other organ system in the body.


educate before you vaccinate

One of the big proponents of the alternative vaccination is schedule is Dr. Bob Sears, who pushes the myth is that there are a lot of vaccinations. And tries to sell a lot of nonsense on his website, but that’s a different story. The meme to the left is one that promoted by a lot of vaccine deniers (or again, vaccine delayers) that the number of vaccines has increased over the years. And, yes it has, partially because we have a lot of new vaccines since the 1980’s, but also, we have more scientific evidence that has fine-tuned the vaccine schedule to prevent diseases that can harm.

This unscientific myth has it’s basis on a belief that somehow all of these vaccines are going to damage the immune system, because “that’s just too many antigens for the young child’s immune system.” Or the vaccine deniers/delayers invent preposterous claims these excess vaccines “use up” the immune system (yes, use up). Or that because vaccines aren’t natural, they mess up the immune system. I’m sure there are other anti-scientific claims, I may not have looked hard enough.

Of course, I’d like to see the evidence for these claims. Anyone? Is there a peer-reviewed paper somewhere that establishes that anyone, a baby, child or adult, other than those with chronic diseases, has an immune system that cannot tolerate the extremely low number of antigens from vaccines?


The medical and scientific evidence tell us a completely different story.

  • Mark Crislip, in the Quackwatch article, Do Children Get Too Many Immunizations? The Answer is No stated that, “delaying vaccines increases the time during which children are susceptible to certain diseases, some of which are still fairly common. Chickenpox, whooping cough, influenza, and pneumococcus still cause hospitalizations and deaths in previously healthy children. Spacing out or separating vaccines will also require more doctor visits, which will increase overall costs as well as the number of times the children must experience any associated discomfort and stress.”
  • Paul A. Offit, MD Charlotte A. Moser, BS concluded that, “at the heart of the problem with Sears’ schedules is the fact that, at the very least, they will increase the time during which children are susceptible to vaccine-preventable diseases. If more parents insist on Sears’ vaccine schedules, then fewer children will be protected, with the inevitable consequence of continued or worsening outbreaks of vaccine-preventable diseases. In an effort to protect children from harm, Sears’ book will likely put more in harm’s way.”
  • Once again, Crislip, in the Science Based Medicine article Alternative Vaccination Schedules opined that, “the preponderance of information in the medical literature on vaccinations is as clear as any topic in medicine.  Vaccines are effective and they are safe.  The best bet for keeping your child, and your community, healthy is to get vaccinated and to do it on schedule.  There are people who see the issue differently, and is often the case, the reasons are more subtle and complicated that one would except.  And there is still much to be understood as to why people do and do not participate in the vaccination schedule.”

Please help me out by sharing this article. Also, please comment below, whether it's positive or negative. Of course, if you find spelling errors, tell me!

There are two ways you can help support this blog. First, you can use Patreon by clicking on the link below. It allows you to set up a monthly donation, which will go a long way to supporting the Skeptical Raptor
Become a Patron!

Finally, you can also purchase anything on Amazon, and a small portion of each purchase goes to this website. Just click below, and shop for everything.

But there’s more

Let’s take a look at what actually happens in the real world with children’s immune systems. In this paper, researchers discovered that:

  • In each cubic meter of air, there are between 1.6 million and 40 million viruses.
  • In each cubic meter of air, there are between 860,000 and 11 million bacteria.

A child inhales about 5 liters of air per minute (or about .005 cubic meters), so a few hundred thousand viruses and bacteria are inhaled every minute every day of the year. And the researchers discovered that many were unknown species of viruses and bacteria, so the immune system has to adapt to them with each breath.

Thus, the 25-30 antigens from vaccines (depending on the age of the child and the number of different flu vaccines that they’ve received) is not even a significant number compared to the millions upon millions of viral and bacterial antigens that enter a child’s lungs every day or week. The tiny number of antigens introduced by vaccines barely register on the immune system’s massive and robust power to deal with antigens.

The antivaccination cultists fail to realize the incredible power of the immune system. It “memorizes” literally billions, if not a 1000 times more, of antigens. The handful of antigens contained by vaccines are critical because of the virulence and danger to human health of those particular pathogens–the immune system just adds that information into its memory bank, it doesn’t get overwhelmed by it.

The complicated and powerful immune system doesn’t get weakened by the “knowledge” from the vaccines. It just moves on to the next antigen, one of the few million that it sees every day. The immune system does not get weaker, unless you have chronic diseases or malnutrition. You can’t make it stronger, but vaccines cause it to adapt to that particular antigen, so that it “remembers” what to do the next time it encounters that antigen.


This is easy. Vaccines simply cause the development of adaptive immunity to a pathogen or antigen. This is something that happens a millions of times a day in a healthy child, teenager, and adult. If the vaccine denialists could bring one tiny bit of evidence that vaccines did something different than cause that adaptive immunity, then we could talk. But they can’t.

As Paul Offit summarized in Addressing Parents’ Concerns: Do Multiple Vaccines Overwhelm or Weaken the Infant’s Immune System?:

Current studies do not support the hypothesis that multiple vaccines overwhelm, weaken, or “use up” the immune system. On the contrary, young infants have an enormous capacity to respond to multiple vaccines, as well as to the many other challenges present in the environment. By providing protection against a number of bacterial and viral pathogens, vaccines prevent the “weakening” of the immune system and consequent secondary bacterial infections occasionally caused by natural infection.

So more evidence that vaccines do not do what vaccine deniers claim they do. And they do precisely what scientists think they do–save lives.

So, multiple vaccinations weakens the immune system? Definitely a myth unsupported by real science.

Editor’s note: This article was originally published in October 2013. It has been completely revised and updated to include more comprehensive information, to improve readability and to add current research.

Key citations:


The Original Skeptical Raptor
Chief Executive Officer at SkepticalRaptor
Lifetime lover of science, especially biomedical research. Spent years in academics, business development, research, and traveling the world shilling for Big Pharma. I love sports, mostly college basketball and football, hockey, and baseball. I enjoy great food and intelligent conversation. And a delicious morning coffee!