Types of Vaccines

Definition

Preparations that train the immune system to recognise a specific pathogen, classified by what form of the pathogen or its components they contain.

Key points

• Live attenuated vaccines use a weakened but living pathogen and give strong, long-lasting immunity; examples include BCG (tuberculosis), oral polio, and measles vaccines.
• Inactivated (killed) vaccines use a dead pathogen and are safer but often need booster doses; the injectable polio (Salk) vaccine is an example.
• Subunit, toxoid, and conjugate vaccines use only parts of the pathogen or its inactivated toxins; the tetanus and diphtheria toxoids and the hepatitis B vaccine fall here.
• Newer platforms include mRNA vaccines (which deliver genetic instructions so cells make a harmless viral protein) and viral-vector vaccines; both were used widely against COVID-19, including India's Covaxin (inactivated) and Covishield (viral vector).
• India's Universal Immunisation Programme provides free vaccines against diseases such as tuberculosis, polio, measles, tetanus, hepatitis B, and others.

Why it matters for CAPF

The live versus killed distinction, BCG and oral polio as live vaccines, toxoids for tetanus, and the new mRNA and viral-vector platforms used against COVID-19 are current and recurring public-health facts.

Common confusion

Live attenuated vaccines use a weakened living pathogen, not a dead one; killed vaccines use a dead pathogen and usually need boosters. An mRNA vaccine does not contain the virus itself, only instructions for cells to make a single harmless viral protein.

Related concepts

concept vaccines and immunity, concept types of immunity, concept antibiotics vs antivirals

Parent note

diseases and public health