Vaccine

Vaccines are the preparation of killed or living microorganisms that produce immunity when administered into the body. Immunity is defined as the ability of the body to resist diseases.

Discovery of vaccination: Smallpox was the first disease ever controlled by vaccination.

Immunity and its types

• Immunity is the ability of a person to fight against disease-causing pathogens. The study of immunity is called immunology. There are two types of immunity:
• Natural or in-born immunity: This type of immunity has been present in the body since birth.
• Acquired immunity: The immunity acquired after birth or during the lifetime of an individual is known as acquired immunity. It may be active or passive.

i.Active immunity: This is produced by injecting a small quantity of antigen called the vaccine into the body.

ii.Passive immunity: In this immunity, the body does not produce antibodies, instead the readymade antibodies from some other animals are introduced for protection against a particular disease.

Types of vaccines

i.Killed vaccine: These vaccines are prepared by killing the pathogenic organisms by heat or UV- rays or alcohol or formalin or phenol, eg Typhoid vaccine and Cholera vaccine.

ii.Toxoid: These vaccines are prepared by destroying the toxic property of the toxins produced by organisms but retaining its antigenic property, eg. Tetanus toxoid and Amtidiphtheria toxoid

iii.Attenuated living vaccines: The pathogen is made weakened and non-virulent Examples- Oral Polio Vaccine (OPV), Bacille Calmette Guerin (BCG), Mumps, Measles, Rubella (MMR) vaccine, etc. provides active life long immunity.