Vaccines: How Do They Work?

What are vaccines?

Vaccines contain either a killed or weakened form of  a virus or bacteria.  The idea is to inject people with the killed or weakened form of the pathogen to give the immune system the ability to build up an immune response to a specific pathogen without actually infecting the individual and making them sick.  This allows the immune system to respond stronger and faster if the individual actually does contract the pathogen.

Image: ; this gives a more technical description of the actual scientific techniques used in creating some vaccines.

How do they work?

When the killed/weakened form of the pathogen enters the body, the immune system identifies an antigen, which is a substance that the body notices is foreign.  Then, the body releases antibodies, proteins that attack the foreign substances in the body.  The body also generates immune response cells, some of which attack infected cells in the body and others help generate more antibodies.  In the case of an immune response to a vaccine, after the body has neutralized the “threat,” which was really never a threat to the individual due to the weakened form of the pathogen, the immune system generates memory cells.  These cells remember the pathogen and, when they interact with the pathogen again, they can then generate the same response faster and stronger (this is known as secondary response).

So what else is in vaccines?

According to the CDC, vaccines contain more than just a weakened or killed pathogen.  They also contain extra fluid to suspend proteins in and preservatives.  Here are some substances commonly found in vaccines:

Aluminum: Aluminum salts are used to help make the immune response stronger.  It makes parts of the vaccine more soluble, meaning it dissolves better in its liquid, and it also helps the immune system target the antigens.

Formaldehyde: This is sometimes put into vaccines to neutralize any active viral or bacterial product, but according to the CDC it is, for the most part, removed before use.

Thimerosal: There has been a lot of controversy over the use of this, because thimerosal has mercury in it.  This is there to prevent the bacteria or viruses that are only weakened from multiplying.

All of these ingredients have been rigorously tested and are only applied in small amounts.  Additionally, they all form polar compounds, which dissolve readily in water and therefore leave the body very quickly.  The harmful substances we should be worried about are those that are nonpolar, which build up in our fat tissue and tend to stay there for long periods of time.  For more descriptions on this, see the GMO’s post:

There will be another post shortly about herd immunity, but for those interested here’s an interesting and fun game that teaches the history of vaccinations:

Works Cited


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