Kids Love Dr. Barton

How Vaccines Work

by Dr. Douglas Barton, M.D., Pediatrician 09/18/2008

So what exactly are all those vaccines doing?

I’m going to address a very simple (for me) subject next:  the vaccines themselves and how they work. It seems that a lot of the misinformation out there comes from a misunderstanding of what vaccines actually do when they get into the body.

Vaccines come in two forms. The first form is made up of little tiny parts of the bacteria or virus that we hope to protect you from. When these little tiny parts are put into the human body, the body generates what are called immunoglobulins. Since there is enormous variation in immunoglobulins, the body eventually finds one of these proteins that actually “fits” the tiny bit of bacteria or virus.  Once this protein matches (“recognizes”) the tiny part, it “sticks” to it.

Sticking to the particle allows the protein to then send out a signal to the body’s infection fighting systems to make lots more of these proteins that “fit.” Signals also are sent out to attack anything that fits that particular protein now or in the future. For example, a small piece of tetanus (the bacteria Clostridium tetani) is put into the body, a protein recognizes it, the protein sends out signals to make a lot more of that protein and also to fight off anything looking like that small piece of tetanus. This makes the body MUCH more responsive to tetanus the next time the body sees it and allows the body to fight it off before it becomes a full-blown infection.

The second form of vaccine is live virus. Measles, chicken pox and rotavirus vaccines actually have the whole virus instead of a piece. These whole viruses have been modified however, so they are unable to create full-blown disease in a person. Just like with the tiny pieces, the whole virus activates a similar response making the body much more sensitive to the virus and allowing it to fight it off in the future. Once the body learns to make the necessary protein the first time, it can make vast amounts of it in the future in a very short time frame which is how a tetanus shot can prevent illness for 10 years or longer. This process has been demonstrated to occur even in the very youngest of our children. Some tiny bits of virus or bacteria cause a more robust response in older children and some require a carrier protein to create a good response. This would be why some vaccines are given very early (hepatitis B) to young people, some are bound to special proteins (HIB vaccine) and some are given later (the meningitis vaccine).


Dr. Douglas Barton is a pediatrician with SSM Medical Group in Lake Saint Louis and Warrenton.


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