How an understanding of how the immune system

How it
Works

In
order to fully understand how vaccines work, there must first be an
understanding of how the immune system functions against foreign microbes. When
the body is exposed to harmful bacteria, the immune system is triggered to do three
key things: identify, eliminate, and prepare. White blood cells known as
macrophages identify the invading microbes by their unique set of molecules called
antigens that cover their surface. Once identified, most of the microbes are
engulfed by the macrophages leaving behind only the antigens. These antigens
are then recognized by lymphocyte cells, which trigger the next line of defense
called adaptive immunity. This is when the two major kinds of lymphocytes take
action, T cells and B cells. Since these cells have been pre-exposed to the
antigens, these killer T cells are able to locate and destroy cells that have
been infected by the microbes. Other T cells called helper T cells work to
stimulate killer T cells. B cells are responsible for secreting millions of
antibodies that fit perfectly together with the antigens. The immune system
stores these antibodies because they are crucial in any future encounters with
similar microbes. If the body is every exposed to these microbes in the future,
it will activate the antibodies and terminate the invading microbes much
quicker. Even though this system works most of the time, people still get sick
and may die from infectious diseases. Sometimes the invading microbe is too
strong and divides at a rate that overwhelms the immune system. Other times,
the person’s immune system is just too weak, like that of a babies or an
elderly person. This is where vaccines come into play. A vaccine is basically a
weakened or dead version of the disease that is injected into the body in order
to allow it to create its antibodies without getting sick.

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Types of
Vaccines

Live, Attenuated
Vaccines:

These
vaccines are created by taking a live form of a specific infectious disease and
subjecting it to a chemical or biological form of treatment in order to weaken
the microbes. Once the microbe is weakened, it can then be injected into a body
with a healthy immune system. This allows the body’s immune system to go through
its natural process of creating antibodies for this disease and preparing
itself for when it comes across the full-blown live version of the disease. This
type of vaccine works well in providing lifelong immunity to the infectious
disease. However, the downsides to this form of vaccine can be that a microbe
may mutate and cause the disease in the person. Another downside is that it can’t
be given to everyone. People with damaged or weakened immune systems can’t have
this vaccine because there is a much higher risk that they will actually catch
the disease.

 

Inactived Vaccines:

Inactivated
vaccines contain dead microbes of a specific disease. This can be done by
subjecting the microbes to heat or chemicals, while still having them remain
antigenic. The downside to this kind of vaccine is that it is much less
effective than the live, attenuated vaccines. Since the microbes in these
vaccines are inactive, this means that once they enter the body, they can’t
divide and multiple unlike the live, attenuated vaccines. The antibodies
created for this disease will be limited to the amount of antigens that it was
introduced to through the vaccine.

 

Toxoid Vaccines:

When
it comes to viruses that secrete toxins, a toxoid vaccine may be administered
for immunization to the virus. It has been discovered that toxins within
viruses can be inactivated by treating them with a solution of formaldehyde and
sterilized water. Keeping in mind, this vaccine works only against viruses in
which toxicity is the main concern for illness.

 

 

Subunit Vaccines:

This
vaccine method only uses antigens from the virus that best stimulate the immune
system to create the antibodies necessary to fight it off. Subunit vaccines can
be created in one of two ways: they can be grown in the lab and its antigens
collected, or the antigen molecules can be produced from the microbe using recombinant
DNA technology.

 

Conjugate Vaccines:

Conjugate
vaccines are used for bacteria that have a polysaccharide coating on their
surface. The polysaccharide coating of these bacteria make it so that young immune
systems can’t recognize them and therefore a response cannot be launched.

However, when polysaccharides are linked to antigens or toxoids from a bacterium
that can be recognized by the young immune system, this issue no longer exists.

The immune system is then able to react to polysaccharide coatings, protecting
against the disease causing microbe.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The Future
of Vaccines

While
still in development, DNA vaccines seems very promising in become the
predominant vaccine in the near future. Unlike the traditional methods of
vaccination, DNA vaccination is the process of injecting someone with the gene
that codes for the specific protein in which the immune system responds to.

This means that once the DNA has entered your cells, the body can then produce
the protein itself. Once these proteins are produced, the body naturally has an
immune response and begins to create those memory T & B cells.

Advantages:

–      
The
body will continue to be exposed to the protein until a solid immune response
is developed.

–      
Very
low cost. Purifying DNA is much easier and cheaper than purifying a protein.

–      
DNA
is much more stable and long lasting. Proteins degrade over time.

Disadvantage:

–      
Getting
the DNA to survive in the cells long enough to create the immune response

 

 

 

 

 

 

 

 

 

 

 

 

 

Vaccines
& Autism

The
debate on weather vaccines cause autism all started in 1998 when Andrew
Wakefield, a British gastroenterologist published a paper linking the MMR
vaccine to autism. The paper discussed eight children who began to develop
symptoms of autism shortly after receiving the vaccine. This drove researchers
to do extensive studies on the linkage between vaccines and autism for the
years to come. Today, countless studies have been conducted and all have failed
to show any correlation between vaccines and autism. A popular belief among those
who believe that vaccines cause autism is that the mercury-containing preservative,
thimerosal in vaccines causes the disorder. However, this type of mercury,
ethylmercury is not the same as the methylmercury found in fish. High exposure
to methylmercury have been shown to pose harmful neurological effect, but not
much research had been done on ethylmercury at the time. In 2004, the Institute
of Medicine analyzed this issue and published a final report which concluded
that this hypothesis was false.