What Is A Vaccine? How Vaccines Work

what is a vaccine

What Is A Vaccine?

Understanding How Vaccines Work

While there has been a great deal of discussion about vaccines, many people don’t actually understand some of the basic facts about them.

This article sets out to establish what vaccines are, exactly how they work and what types of vaccines exist.

With all the debate about vaccination, this page articulates what exactly it is vaccines do and why it’s so important that these life saving, preventative tools are given the appropriate respect they deserve.

If you’ve ever wanted to know more about vaccines, then read on to find out more.


The Definition Of Vaccine

What Is A Vaccine?

The Definition Of Vaccine

To provide a quick explanation, a vaccine is simply a biological preparation which when effective, provides an immunity from a disease.

Each vaccine contains a compound that resembles the disease and is most often made from either a dead or weakened form of that disease.

By allowing this weakened compound into your system, your body’s immune system is then stimulated and proceeds to recognize the newly introduced agent as a threat.

Not only does it destroy the foreign material, your body then also keeps a record so that any future similar threats, such as the disease itself, will be recognized and killed immediately before they can harm your body.

Because vaccines contain the weakened version of the disease, it does not pose a threat to most healthy people, in the overwhelming majority of the cases with which it’s administered.

More information on the outcomes of vaccinations can be found in this comprehensive study that analysis vaccines and the effects on those who received them.

So What Does This Really Mean?

A vaccine is mostly an altered and weak strain of a condition that helps you develop an immunity without compromising your immune system


are vaccines safe

Are Vaccines Safe?

What Does The Science Really Say?

In the overwhelming majority of cases, vaccines are safe.  There are some small risks associated with some vaccinations, but those must be disclosed at the time of the vaccine being administered.

In the USA, any future vaccines must go through rigorous testing and evaluation before being marketed.

To get a vaccine into the market, it must be gauged by both the F.D.A as well as the C.D.C (Centers for Disease Control and Prevention), once scrutinized thoroughly, then and only then, the vaccine may be approved.

What About Mercury In The Vaccine?

Some vaccines contain a minutely small trace of mercury in a form called thimerosal, which is included for its antifungal properties.  In the USA, mercury-containing thimerosal was removed as an antifungal preservative from all childhood vaccinations, and some  flu vaccines, so it’s not as much of a concern anyway.

It seems that a lot of the hype surrounding vaccine safety revolves around mercury and its assumed safety concerns for children, but knowing now that most vaccines for children simply do not contain mercury anyway, means a lot of the contrary advice coming from anti-vaccination groups is misinformed.

This isn’t to say vaccines don’t come with risks because they do and we’ll be discussing them in the next segment of this article.


vaccine side effects

Vaccine Side Effects?

What Are They?  Are They Dangerous

While vaccination is mostly safe, there are risks involved as many of the possible vaccines have potential side effects.

Side effects of a vaccination may be something very small and seemingly innocuous like mild bruising, a raspy, sore throat or a little itchiness, but may extend all the way to heightened allergies, pneumonia or even permanent brain damage.

It’s all completely dependant on the person and the actual vaccine because no two are alike or come with the exact same side effects.

For Those wanting to know more about the side effect of the vaccination they are receiving, all the information should be readily available to you at the place of reception.

The website vaccine.gov offers an excellent rundown on many of the most popular vaccines and their side effects here.

So, Are Vaccines Completely Safe?

The short answer is yes “with a but”.  There are rare side effects from some vaccinations, and a small proportion of those are actually severe.




what are antigens
What Are Antigens?

Microbe I.D

You may already know that your body’s white blood cells are the cells that are responsible for getting rid of diseases in your body.

A certain type of white blood cell known as a macrophage actually “swallows” these microbes and destroys them.

How exactly do they recognize foreign material?

Every cell in your body has a surface that is unique to you.

Foreign material, germs, and bacteria have a different surface that macrophages can detect.  They recognize that bacteria are not a natural member of your body while leaving your body’s cells alone.

Understanding Antigens

The specific molecules on bacteria that identify it as foreign are known as “antigens.” (1)

Every different microbe has a unique set of antigens which are important when creating a vaccine.

After macrophages engulf and digest the microbe, they save the antigens and take them back to the lymph nodes, which are an important part of your immune system.

There, they display the antigens so that other white blood cells known as lymphocytes will know which cells are dangerous.

Long Story Short Version

Antigens are substances that will elicit a reaction in the form of antibodies in a host.



lymphocyte shield

Protecting Against Microbial Dangers

When Lymphocytes Fight Back

Lymphocytes work to not only kill dangerous microbes but will also destroy any of your own cells that have already been infected.


While there are a few different types of lymphocytes, you should be most aware of B cells. These types of cells make molecular “weapons” known as antibodies. (2)

Antibodies are designed to stick to antigens and, when released, will coat the antigens on the microbes.

Because your body already knows the surface of the foreign microbes, the antibodies will only stick to the dangerous cells and will leave your healthy cells alone.

The antibodies on the surface of these cells signal your body’s white blood cells to destroy the microbes, getting rid of any dangerous material that still exists. Gradually, the disease will disappear from your body.

So, What Are Lymphocytes?

They are subtypes of your white blood cells that help defend against microbial dangers




what are memory cells

What Are Memory Cells?

Memory Cells and Immunity

After your body eliminates the disease, some of the lymphocytes are turned into memory cells.
Memory cells, like their name suggests, will remember the infectious microbes and quickly recognize how to stop the infection if it appears again. (3)

It’s one of those truly amazing functions of the human body that occur at a microscopic level.

Vaccines and Infection

Vaccines work in your body by acting like a natural infection. For example, the yellow fever vaccine contains a weak form of a virus that won’t actually cause disease.

Your body’s cells can’t recognize that the virus isn’t dangerous so they destroy it and you’re left with a supply of memory cells which will then protect you against yellow fever.

So What Are They Exactly?

Memory cells are a type of memorizing cell that remembers infectious dangers.


types of vaccines

What Are The Types of Vaccines?

What Do They Do?

There are many different types of vaccines.  Some of the vaccines are live but weakened like the yellow fever vaccine.

Let’s take a look at a couple of popular vaccines:

Inactivated Vaccine

Another type is an inactivated vaccine.
Scientists produce this type of vaccine by killing the microbe.

While your body will still recognize the dead vaccine as dangerous, you generally need a few doses before your body has a strong immune response to the vaccine.

Subunit & Toxoid Vaccines

Subunit and Toxoid vaccines are also available to prevent some diseases.
A subunit vaccine isn’t the entire microbe but contains only the antigen that stimulates your immune system.

You can think of it as being a very small portion of the entire disease.
Toxoid vaccines are designed to protect you from bacteria that secrete toxins or chemicals.

They inactivate the toxins and your body learns how to “fight” off the natural toxin. A tetanus vaccine is one example of this.

What’s The Take Away Here?

Not all vaccines are exactly the same and there are some created differently fo unique purposes.



cancer vaccine

Are There Cancer Vaccines?

What Are They?

The most recognizable cancer vaccination is known as the HPV (human papillomavirus) vaccine.  This can help to prevent possible cancers and ailments such as genital warts, cervical cancer, and rectal cancer.

There are currently clinical trials underway looking to finding serviceable vaccinations for breast cancer, melanoma, bladder cancer, brain tumors, colon cancer, and leukemia, to name a few.

There is promise in this area and with a number of potential lives saved, it could be one of the most important areas of research ever undertaken.

What Does This Mean?

There are limited cancer vaccines at the moment but hopefully, the future may well have an abundance of them, maybe even one for the common cold



how vaccines work

What Is A Vaccine?


Once your body is trained to resist a certain disease, you are immune to it.
Understanding how vaccines work to cause immunity without actually causing illness is important.

Although vaccines have been around for dozens of years, scientists are continuing to work on developing vaccines for diseases such as HIV, multiple sclerosis, and certain allergies.

We hope you enjoyed the article “what is a vaccine”.  Please feel free to leave a comment in the section below.

About the author

S James

1 comment
Proscience - November 6, 2017

Anti-vaxers are absolutely nuts. Science has shown vaccines to be effective at saving lives and preventing deaths. This ignorance of the facts isn’t just harmless, it’s KILLING people. People need to wise up and do what’s right. This article is good because it’s neutral but it needs to take a harsher tone towards those who ignore the science. There’s no excuse for science denial.

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