How Do Vaccines Work

Hopefully you have already read about the immune system. If not, click the link above.

Here are some key points to understanding vaccination.

“First lets go over the Humoral Response:

Your B cells have membrane bound antibodies.

Each B Cell has thousands of the same membrane bound antibody and some B cells have different antibodies than others.

That means there are likely millions of different B Cells in your body at this given moment. Each that respond to a different foreign pathogen.

When you are exposed to a pathogen it may take a long time for it to run into the specific B Cell that can bind to it. This time allows the pathogen to reproduce and become threatening.

However once it binds to the right B cell that B Cell reproduces into effector B cells or plasma Cells and memory B Cells.

The effector B Cells begin producing antibodies and the memory B cells stay around in larger numbers in case that same virus comes back your body will be prepared to fight it.”


“B Cells will usually bind to this in stead of the actual pathogen itself. This allows for B cell differentiation even if your Innate response is adequate.

It is important to note that this is mediated by CD4+ T Cells.

The too will bind to this MHC II complex.

And like B cells they differentiate into effector T Cells and Memory T Cells.

Again this prepares your body for another encounter with the same pathogen.

Essentially what these CD4+ T Cells do is release cytokines that tell other leukocytes to come to the location of that pathogen.

Leukocytes like phagocytes that will eat the pathogen, CD8+ T Cells that will poison the pathogen, and B Cells that will release antibodies to opsonize the pathogen.”


Types of opsinizaton

“Antibodies can do many things to a pathogen besides marking it as a foreign body like

  • Neutralization- Renders pathogen ineffective
  • Agglutination- Clumps Pathogens many together
  • Precipitation- Similar to agglutination “

You should be able to see that exposure to a pathogen is good because it allows your body to develop a specific defense to said pathogen, but in a non controlled environment exposure is usually to great and puts you at risk.

This is what is so good about vaccines, usually the vaccine is a very low dose of a  weakened strand of some pathogen that allows your body to easily and safely create a specific immunity to said pathogen.