Vaccines Are Not Calibrated by Weight or Age

Vaccine Basics

Talk to your pediatrician if you have any questions about your child's vaccines.
Talk to your pediatrician if you have any questions about your child's vaccines. Photo by Getty Images

One of the anti-vaccine arguments that is used to scare parents from vaccinating and protecting their kids is that vaccines are not calibrated by weight or age, so that infants end up getting the same dosage of a vaccine as an older child or an adult.

Why does "an 8 pound 2-month-old receive the same dosage as a 40 pound five-year-old?"

Vaccines for Children and Adults

Do infants and adults really get the same vaccines?

Let's consider the hepatitis B vaccine.

You can read a lot about the hepatitis B vaccine if you spend too much time on anti-vaccine websites, including that:

  • infants get 5 or 10 times the dosage as an older child or adult who gets the same vaccine
  • there is doubt that the hepatitis B virus even exists
  • the hepatitis B vaccine causes multiple sclerosis
  • the AIDS "virus" was introduced into the American population via a hepatitis B experiment

Do you believe any of these statements or conspiracy theories?

If you don't believe that hepatitis B is a made-up virus or that HIV was caused by a hepatitis B vaccine experiment, then why would you believe anything else you read on an anti-vaccine website?

So do children and adults get the same dosage of the hepatitis B vaccine?

While children all get the same dosage of the pediatric formulations of either the Recombivax HB or Engerix-B vaccine, there are actually adult forms of these vaccines which contain twice as many antigens.

So no, infants and adults don't get the same dosage of the hepatitis B vaccine.

Vaccine Doses

There are also different formulations based on a child's age for some other vaccines, including:

  • hepatitis A (pediatric and adult formulations)
  • Fluzone Pediatric Dose (6 months to 35 months) vs Fluzone
  • DTaP (pediatric) vs Tdap (10 and over)

    Vaccines aren't usually dosed based on a child's weight or age though, so except in these few instances, it doesn't matter that "an 8 pound 2-month-old receives the same dosage as a 40 pound five-year-old."

    How Vaccines Work

    You have to understand a little about how vaccines work to know why the vaccine dose doesn't really matter as much as some folks think it should.

    The small amount of antigens in the vaccine don't actually travel throughout your body to work, like an antibiotic or other drug does. They just stimulate the immune cells near where the vaccine was given and then those cells go and do their job throughout your body.

    That's why kids usually all get the same vaccine dose, and sometimes, the same vaccine that an adult might get. The vaccine doesn't typically need to be calibrated by weight or age to work.

    Get Educated. Get Vaccinated. Stop the Outbreaks.

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