Which of the following is classified as a live attenuated vaccine?

NORCET 9 Prelims-2025

Pharmacology

Easy

Appeared in: NORCET 9 Prelims-2025

Explanation

The Measles, Mumps, and Rubella (MMR) vaccine is a classic example of a live attenuated vaccine.
This means it contains weakened (attenuated) forms of the live measles, mumps, and rubella viruses.
These weakened viruses are unable to cause disease in healthy individuals but are strong enough to stimulate a robust and long-lasting immune response, mimicking natural infection.

Option A: This is a toxoid vaccine, not a live vaccine. It is made from an inactivated toxin produced by the Clostridium tetani bacteria.
Option B: This is an inactivated (killed) vaccine, as clearly stated in its name. The poliovirus has been completely killed with chemicals and cannot replicate.
Option D: This is a recombinant subunit vaccine. It is produced using genetic engineering to create a single viral protein (Hepatitis B surface antigen, HBsAg), not the whole live virus.

Visual 1: Infographic - A chart illustrating the four main types of vaccines: Live-attenuated, Inactivated (Killed), Subunit/Recombinant, and Toxoid. Each section should show a simple diagram of the vaccine component (e.g., weakened virus, killed virus, protein part, inactivated toxin) and list key examples like MMR, IPV, Hepatitis B, and Tetanus.

Clinical Relevance

Nursing practice connection: This is primarily an exam-oriented knowledge point with limited direct bedside application, so retain Classification of vaccines by type (live attenuated, inactivated, toxoid, subunit) as background academic context rather than a clinical decision trigger.
Understanding vaccine types is critical for safe administration. Live attenuated vaccines like MMR are generally contraindicated in immunocompromised individuals (e.g., those with HIV, undergoing chemotherapy) and pregnant women because the weakened virus could potentially cause infection in a weakened immune system.
In contrast, inactivated, toxoid, or subunit vaccines do not contain live pathogens and are generally considered safe for these patient populations.
What if? If the patient was a pregnant woman needing protection against rubella, the MMR vaccine would be contraindicated. She would be advised to receive the vaccine after delivery to avoid any potential risk to the fetus.

How to Approach the Question

Identify the core concept in the question: The question asks to identify a 'live attenuated vaccine'.
Define 'live attenuated vaccine' in your mind: A vaccine containing a weakened but still living version of the pathogen.
Systematically evaluate each option against this definition:
Tetanus toxoid: 'Toxoid' means it's made from a toxin, not a live organism. Eliminate this option.
Inactivated Polio Vaccine: 'Inactivated' means killed. Eliminate this option.
MMR: Recall that Measles, Mumps, and Rubella are viral diseases and the combined vaccine is a well-known live vaccine. This is a strong candidate.

Concept Tested & Keywords

Concept Tested: Classification of vaccines by type (live attenuated, inactivated, toxoid, subunit).
Stem keywords: live attenuated vaccine, classified
Lead-in keywords: Which

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