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

Vaccination is based on the memory of the immune system. A vaccine is introduced into the body to produce immunity to a specific disease. The antibodies produced against the antigens in the vaccine neutralise the pathogenic agents during actual infection.

Importance:

• Vaccination is a way to prevent diseases.
• It helps the body build resistance to specific diseases.
• It teaches the body to recognise and fight the disease effectively if it is exposed to it in the future.

Working: 

• Vaccination teaches the body to recognise new pathogens causing disease.
• It stimulates the body to produce antibodies against pathogen antigens.
• It also primes immune cells to remember the types of antigens.
• This allows a faster response when the same pathogen enters the body again.
• When the body responds to the vaccine, it builds an adaptive immune response that helps fight an actual infection.

Forms of Vaccines:

• A protein or sugar from the pathogen.
• A dead or inactivated form of a pathogen.
• A toxoid containing toxin produced by a pathogen.
• A weakened (attenuated) pathogen.

Early-Life Vaccination:

• Soon after birth, a baby is given a vaccine for tuberculosis.
• At 1.5 months of age, vaccinations are given for diphtheria, whooping cough, tetanus, and polio.
• Two more doses of these vaccinations are given at one-month intervals.
• The vaccines for diphtheria, whooping cough, and tetanus are combined into a single triple vaccine and given as an injection.
• The polio vaccine is given orally as drops.

Immunisation is the process by which the body becomes protected against a disease. It describes the changes that occur in the body after vaccination.

Role of Immune Memory:

• The principle of immunisation is based on the immune system's memory.
• Vaccines generate memory B-cells and T-cells.
• On subsequent exposure, these cells recognise the pathogen quickly and produce a large number of antibodies to neutralise the invaders.

Passive Immunisation:

• In some cases, a quick immune response is required, such as in tetanus.
• In such cases, preformed antibodies or antitoxin are directly injected.
• In snakebite cases, the injection given also contains preformed antibodies against snake venom.
• This type of immunisation is called passive immunisation.

Recombinant Vaccines:

• Recombinant DNA technology enables the production of antigenic pathogen polypeptides in bacteria or yeast.
• Vaccines produced by this method can be made on a large scale and are more widely available for immunisation.
• The hepatitis B vaccine produced from yeast is given as an example.

• Vaccination and immunisation work on the immune system's memory.
• A vaccine may contain a weakened pathogen, an inactivated pathogen, or antigenic proteins.
• The body produces antibodies against these antigens.
• Memory B-cells and T-cells enable a faster response during later exposure.
• Passive immunisation involves direct injection of preformed antibodies or antitoxins.
• Examples of passive immunisation include tetanus and snakebite treatment.
• Vaccines may be made from protein or sugar from a pathogen, a dead or inactivated pathogen, a toxoid, or a weakened pathogen.
• Antigenic polypeptides can also be produced using recombinant DNA technology in bacteria or yeast.