Vaccination and Immunization

A preparation containing specific antigens that is administered to induce temporary or permanent immunity against a particular disease is called a vaccine.

The principle of immunisation or vaccination is based on the property of memory of the immune system. “Vaccination is the process of administering a vaccine into the body or introducing a vaccine into the body to produce immunity to a specific disease.” The antibodies produced in the body against these antigens would neutralise the pathogenic agents during actual infection.

• Vaccination is a way to prevent diseases.
• When we get vaccinated, it helps our body build resistance to specific diseases.
• The vaccine helps our body learn to fight the disease, so if we ever come in contact with it in the future, our body is ready to defeat it.

Soon after birth, babies are given a vaccine for tuberculosis to protect them from this serious disease. When the baby is one and a half months old, they are given vaccinations to protect them from:

• Diphtheria (a throat infection)
• Whooping cough (a serious cough)
• Tetanus (which causes muscle stiffness)
• Polio (a disease that can affect movement)

Babies are given two more doses of these vaccinations at one-month intervals to protect them from these diseases fully. Vaccines ensure strong protection against these illnesses.

Vaccination

Types of vaccines:

• The diphtheria, whooping cough, and tetanus vaccines are combined into a single triple vaccine and given as an injection.
• The polio vaccine is given orally (by mouth) as drops.

The process of administering a vaccine to stimulate the immune system and provide protection against infectious diseases is called vaccination.

The antibodies produced in the body against these antigens would neutralise the pathogenic agents during actual infection. Immunisation is the process of the body building up immunity to a particular disease. Immunisation describes the actual changes in the body after receiving a vaccine.

• Vaccines work by fighting the pathogen and then recording it in their memory system to ensure that the next time this pathogen enters the body, it is eliminated far more quickly.
• Once the body can fight against the disease, it is believed to have built immunity for it, also known as being immunised against it.
• The vaccines also generate memory. On subsequent exposure, the B and T cells recognise the pathogen quickly and synthesise a large number of antibodies to kill the invaders.
• If a person is infected with deadly microbes to which a quick immune response is required, as in tetanus, we need to directly inject the prepared antibodies or antitoxin (a preparation containing antibodies to the toxin).
• Even in snakebite cases, the injection given to the patients contains preformed antibodies against the snake venom. This type of immunisation is called passive immunisation.
• Recombinant DNA technology has allowed the production of antigenic polypeptides of pathogens in bacteria or yeast.
• Vaccines produced using this approach allow large-scale production and hence greater availability for immunisation, e.g., hepatitis B vaccine produced from yeast.

• Principle: Works on the immune system's memory. A vaccine (weakened/inactivated pathogen or its proteins) stimulates antibody production and generates memory B and T-cells.
• On Re-exposure: Memory cells quickly recognise the pathogen and produce massive antibodies to neutralise it.
• Passive Immunisation: Preformed antibodies/antitoxins are directly injected when quick response is needed (e.g., tetanus, snakebite).
• Types of Vaccines: Protein/sugar from pathogen, dead/inactivated pathogen, toxoid, or attenuated (weakened) pathogen.
• Recombinant DNA Vaccines: Antigenic polypeptides produced in bacteria/yeast for large-scale production (e.g., Hepatitis B vaccine from yeast).