Tag: antigen load

Aren’t Vaccines Made for Adults?

Have you ever heard someone bring up the argument that vaccines are made for adults, so kids shouldn’t be getting the same dosage?

If they do, you should understand right away that they don’t really understand how vaccines work.

And that they really don’t understand immunology either, for that matter.

Are Vaccines Made for Adults?

To be fair, some vaccines are made just for adults. In fact, some, like the shingles vaccines and high-dose flu shot (has four times the amount of antigen in the regular flu shot) are only for seniors.

Other vaccines, like the rotavirus vaccine, are made just for kids.

And a few vaccines come in different forms depending on your age.

For example, younger kids get the DTaP vaccine, while older kids and adults get a Tdap vaccine. They both protect against the same three diseases (diphtheria, tetanus, and pertussis), but they contain different amounts of antigens. In this case, the Tdap vaccine actually contains 3-5 times less of the diphtheria component as the DTaP vaccine. That’s because before they lowered it, repeated dosing of the original Td vaccine every ten years led to worsening local reactions in some people.

The hepatitis B and hepatitis A vaccines are also available in different formulations for kids and adults, with adults getting twice the amount of antigens.

Most other vaccines though, come in the same form for both kids and adults, including the MMR vaccine and vaccines that protect us against HPV, chicken pox, polio, meningococcal disease, and pneumococcal disease, etc.

Are Vaccines Calibrated by Weight or Age?

Why does this question even come up?

Science event in Washington, D.C. reminding folks that Vaccines Work.
Pediatricians at the March for Science event in Washington, D.C. reminded folks that Vaccines Work. We shouldn’t forget that others also need a reminder of how they work.

It’s because some folks push the myth that infants are getting too high a dose of vaccines, since in most cases, older kids and adults get the very same dose.

They don’t though.

Does that mean that those older kids and adults are getting too low a dose then?

Nope.

You see, vaccines aren’t like antibiotics or other medications. They aren’t typically dosed based on your weight or age and don’t have to build up to a steady state in your blood stream.

That’s right, for most vaccines, it doesn’t matter if your child weighs 8 pounds or 80 pounds.

Why not?

Because the antigens in the vaccine don’t have to travel all around your child’s body in order for them to work!

Understanding the Immune Response to a Vaccine

Instead, the small amount of antigens in a vaccine simply get the vaccine response started near where the vaccine was given, whether that is in their arm or leg (shot), nose (nasal), or small intestine (oral).

“B cells are essentially activated in the lymph nodes draining the injection site.”

Claire-Anne Siegrist on Vaccine Immunology

Antigen-presenting cells (APCs) then take up the antigens and migrate towards a nearby lymph node. It is at these lymph nodes that the APCs activate other cells, including:

  • antigen-specific helper T cells
  • killer T cells
  • B cells

The activated T and B cells then go to work, with many B cells becoming plasma cells, and some T and B cells transforming into memory cells.

This illustration from the NIH and National Library of Medicine helps explain how vaccines work.
This illustration from the NIH and National Library of Medicine explains how vaccines work.

Next, within days to weeks of getting vaccinated, the plasma cells begin producing protective antibodies, which are released into our bloodstreams.

The same thing happens if you are exposed to a disease naturally, which is why it is silly to think that a vaccine could weaken or overwhelm your immune system.

The big difference about getting exposed to a disease naturally vs getting a vaccine? With the vaccine, you don’t have to actually have the the symptoms of the disease or any of its complications to get immunity. In other words, you don’t have to earn your immunity.

What to Know About Vaccine Dosage Myths

The dose of vaccines for kids and adults is not calibrated by weight or age because the immune reaction that helps antibodies travel all through your body starts locally, near where the vaccine was given.

More on Vaccine Dosage Myths

Antigen Counts in Vaccines

Vaccines contain antigens from toxins, viruses, or bacteria that help your body produce antibodies to help prevent future infections.

Of course, we are all exposed to these types of antigens every day.

In fact, experts state that we are exposed to thousands, if not millions, of antigens each day.

Eating. Drinking. Breathing. Touching things. These every day actions all can introduce antigens from viruses, bacteria, parasites, and toxins, etc., into our bodies.

And even though kids get many more vaccines today, and are protected against many more vaccine-preventable diseases than they once were, they actually get far fewer antigens from those vaccines than they once did.

Newer vaccines have a fraction of the antigens that the older DPT and smallpox vaccines once did.

That’s why the popular “too many too soon” anti-vaccine myth shouldn’t scare you from getting your kids vaccinated and protected.

Vaccine Antigen Counts

If you are still stuck on the actual number of vaccines, it is important to “understand that the numbers of antigens given are actually much less than they used to be. This is because we are giving purer vaccines. Vaccines have been isolated down to just the proteins needed to produce protection.”

The antigens are the things in the vaccines that actually trigger the production of antibodies and include antibody-stimulating proteins and polysaccharides.

In 1960, kids got up to 3,217 different antigens from the smallpox, polio, diphtheria, tetanus and whole cell pertussis vaccine.

In 1980, even as MMR replaced the smallpox vaccine, the antigen count in the vaccines kids got was still up to 3,041.

Kids Today Get Purer Vaccines

Even with many more vaccines, the number of different antigens that children will get with today’s immunization schedule is much lower than just 35 or 55 years ago:

  • DTaP/Tdap – 7 antigens
  • MMR – 24 antigens
  • IPV – 15 antigens
  • Hib – 2 antigens
  • Varicella – 69 antigens
  • Prevnar13 – 14 antigens
  • hepatitis A – 4 antigens
  • hepatitis B – 1 antigens
  • MCV4 – 5 antigens
  • HPV9 – 9 antigens
  • rotavirus – 15 antigens
  • Flu – 12 antigens

That’s just 177 different antigens in 12 vaccines that protect children against 16 vaccine-preventable diseases.

That’s still less than the 200 antigens that were in the smallpox vaccine that kids got 100 years ago.

Even considering that kids get multiple doses of many of these vaccines, with today’s complete vaccine schedule, from birth to age 18, including yearly flu shots, they would get a combined total of just 653 antigens. That’s still much less than a single dose of the DTP vaccine that kids got until 1997, when it was replaced by the DTaP vaccine.

With the 1980 immunization schedule, kids got 5 doses of DTP, 4 doses of OPV, a dose of MMR, and a dose of Td, combining to a grand total of at least 15,096 antigens.

Immune System Response to These Antigens

Of course, this is not to say that kids were exposed to too many antigens in vaccines in the past.

“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. ”

Offit et al on Addressing Parents’ Concerns: Do Multiple Vaccines Overwhelm or Weaken the Infant’s Immune System?

Looking at the antigen load of vaccines is simply another way to understand that kids don’t get too many vaccines too soon.

In fact, they get exposed to many more antigens from natural infections. A strep throat infection, for example, exposes kids to at least 25 to 50 antigens. That’s comparable to the antigens in the vaccines that infants get at their two month visit – the DTaP, IPV, HepB, Hib, and rotavirus vaccines combine to just 54 antigens.

But it is not just infections that lead to antigen exposures. Kids are exposed to 2,000 to 6,000 antigens every day and the “vaccines that children receive in the first two years of life are just a drop in the ocean when compared to the tens of thousands of environmental challenges that babies successfully manage every day.”

What to Know About Antigen Counts in Vaccines

Although kids get more vaccines today that their parents and grandparents, they get far fewer antigens from those vaccines.

More About Antigen Counts in Vaccines