Overview of Vaccines, Types of Immunity, and Immunization

Vaccines are used to boost your immune system and prevent serious, life-threatening diseases.

Vaccines “teach” your body how to defend itself when germs, such as viruses or bacteria, invade it.
Vaccines expose you to a very small, very safe amount of viruses or bacteria that have been weakened or killed.
Your immune system then learns to recognize and attack the infection if you are exposed to it later in life. As a result, you will not become ill, or you may have a milder infection. This is a natural way to deal with infectious diseases.

Four types of vaccines are currently available

Live virus vaccines use the weakened (attenuated) form of the virus. The measles, mumps, and rubella (MMR) vaccine and varicella (chickenpox) vaccine are examples.
Killed (inactivated) vaccines are made from a protein or other small pieces taken from a virus or bacteria. Whooping cough (pertussis) vaccine is an example.
Toxoid vaccines contain a toxin or chemical made by the bacteria or virus. They make you immune to the harmful effects of the infection, instead of to the infection itself. Examples are diphtheria and tetanus vaccines.
Biosynthetic vaccines contain manmade substances that are very similar to pieces of the virus or bacteria. The Hepatitis B vaccine is an example.

COMMON VACCINES

Chickenpox vaccine,
DTaP immunization (vaccine),
Hepatitis A vaccine,

Hepatitis B vaccine,
Hib vaccine,
HPV vaccine,

Influenza vaccine,
Meningococcal vaccine,
MMR vaccine,

Pneumococcal conjugate vaccine,
Pneumococcal polysaccharide vaccine,
Polio immunization (vaccine),

Rotavirus vaccine,
Shingles vaccine,
Tdap vaccine,

Tetanus vaccine,
COVID Vaccine

TYPES OF IMMUNITY

Immunity is your body’s ability to recognize germs to prevent them from causing illness. The immune system’s job is to help identify and eliminate dangerous germs that enter the body before they can cause disease or damage. There are two types of immunity: innate and adaptive

INNATE IMMUNITY

Innate immunity is the immune system that is present when you are born. It is your body’s first line of defense against germs.
It includes physical barriers, such as skin and mucous membranes, and special cells and proteins that can recognize and kill germs.
The problem with these special cells and proteins is that they can kill a germ, but once the germ is dead, the innate immune system forgets it.

It does not communicate any information about the germ to the rest of the body. Without this information, the body cannot prepare itself to fight this germ if it should re-infect the body.

ADAPTIVE IMMUNITY

Adaptive immunity is protection that your body builds when it meets and remembers antigens, which is another name for germs and other foreign substances in the body.
When your body recognizes antigens, it produces antibodies to fight the antigens.

It takes about 14 days for your body to make antibodies.
More importantly, the body memorizes this fight so that if its meets the same antigen again, it can recognize and attack more quickly.
Antibody production is one of the most important ways that immunity is developed.

There are two types of adaptive immunity: active and passive.

Active Immunity – antibodies that develop in a person’s own immune system after the body is exposed to an antigen through disease or when you get an immunization (i.e. a flu shot). This type of immunity lasts for a long time.

Passive Immunity – antibodies given to a person to prevent disease or to treat disease after the body is exposed to an antigen. Passive immunity is given from mother to child through the placenta before birth, and through breast milk after birth. It can also be given medically through blood products that contain antibodies, such as immune globulin. This type of immunity is fast-acting but lasts only a few weeks or months.

IMMUNIZATION

Immunization is the process by which an individual’s immune system becomes fortified against an agent (known as the immunogen). The most important elements of the immune system that are improved by immunization are the T cells, B cells, and the antibodies B cells produce.

Memory B cells and memory T cells are responsible for a swift response to a second encounter with a foreign molecule. Passive immunization is the direct introduction of these elements into the body, instead of the production of these elements by the body itself.

Immunization is done through various techniques, most commonly vaccination. Vaccines against microorganisms that cause diseases can prepare the body’s immune system, thus helping immunization.

Immunization can be achieved in an active or passive manner: Vaccination is an active form of fighting or preventing infection.

ACTIVE IMMUNIZATION

Active immunization can occur naturally when a person comes in contact with, for example, a microbe. The immune system will eventually create antibodies and other defenses against the microbe.
The next time, the immune response against this microbe can be very efficient; this is the case in many of the childhood infections that a person only contracts once, but then is immune.

Artificial active immunization is where the microbe, or parts of it, are injected into the person before they are able to take it in naturally. If whole microbes are used, they are pre-treated.

PASSIVE IMMUNIZATION

Passive immunization is where pre-synthesized elements of the immune system are transferred to a person so that the body does not need to produce these elements itself.
Currently, antibodies can be used for passive immunization. This method of immunization begins to work very quickly, but it is short-lasting because the antibodies are naturally broken down, and if there are no B cells to produce more antibodies, they will disappear.

Passive immunization occurs physiologically when antibodies are transferred from mother to fetus during pregnancy, to protect the fetus before and shortly after birth.
Artificial passive immunization is normally administered by injection and is used if there has been a recent outbreak of a particular disease or as an emergency treatment for toxicity, as in for tetanus.
The antibodies can be produced in animals, called “serum therapy,” although there is a high chance of anaphylactic shock because of immunity against animal serum itself.