Which type of vaccine protects against Diphtheria?
- (a)Toxoid
- (b)Live-attenuated
- (c)mRNA
- (d)Viral Vector
Correct — A, Toxoid. Diphtheria is caused not by the bacterium itself but by the exotoxin secreted by Corynebacterium diphtheriae. The vaccine therefore uses a toxoid — the diphtheria toxin chemically inactivated (e.g., with formaldehyde) so it can no longer cause disease but still triggers protective anti-toxin antibodies. This diphtheria toxoid is combined with tetanus toxoid and pertussis antigen in the familiar DPT/DTaP vaccine.
- (b)Live-attenuated — Live-attenuated vaccines use a weakened live pathogen (e.g., BCG, oral polio, MMR). Diphtheria protection targets the toxin, not a live organism, so a toxoid — not a live vaccine — is used.
- (c)mRNA — mRNA vaccines deliver messenger RNA coding for an antigen (used in some COVID-19 vaccines). This platform is not used for diphtheria, whose protection is toxin-based.
- (d)Viral Vector — Viral-vector vaccines use a harmless virus to carry antigen genes (e.g., Covishield/Sputnik V for COVID-19). This is not the platform for the diphtheria vaccine.
Vaccines are grouped by platform: live-attenuated, inactivated (killed), subunit/conjugate, toxoid, mRNA and viral-vector. A toxoid vaccine is used when the disease is caused by a bacterial exotoxin — the toxin is inactivated into a harmless 'toxoid' that still provokes anti-toxin immunity. Diphtheria and tetanus are the classic toxoid-vaccine diseases, delivered together with pertussis as DPT.
The clue is the disease mechanism: diphtheria's harm comes from a toxin, so the vaccine must neutralise the toxin — i.e., a toxoid. The other options are real vaccine platforms placed as traps, but they became household terms mainly through COVID-19 (mRNA, viral vector) or apply to whole-organism diseases (live-attenuated).
- Diphtheria vaccine = toxoid: an inactivated (detoxified) form of the diphtheria toxin.
- It is combined with tetanus toxoid and pertussis as the DPT/DTaP vaccine.
- Toxoid vaccines are used against diseases whose harm comes from a bacterial exotoxin — diphtheria and tetanus.
- Contrast platforms: live-attenuated (BCG, OPV, MMR), inactivated (IPV, Covaxin), mRNA/viral-vector (COVID-19 vaccines).
Diphtheria (a toxin-mediated disease) is prevented by a toxoid vaccine — the inactivated toxin.
- Assuming a 'modern' platform (mRNA/viral-vector) applies to a long-established vaccine like diphtheria
- Confusing toxoid (inactivated toxin) with inactivated whole-pathogen vaccines
UPSC/UPPSC ask 'which type of vaccine' for a named disease, or to classify named vaccines (Covaxin, Covishield, BCG) by platform.
In the context of vaccines manufactured to prevent COVID-19 pandemic, consider the following statements: 1. The Serum Institute of India produced COVID-19 vaccine named Covishield using mRNA platform. 2. Sputnik V vaccine is manufactured using vector based platform. 3. COVAXIN is an inactivated pathogen based vaccine. Which of the statements given above are correct?
- (a) 1 and 2 only
- (b) 2 and 3 only
- (c) 1 and 3 only
- (d) 1, 2 and 3
Answer(b) 2 and 3 only
Same concept — classifying vaccines by platform (vector, inactivated, mRNA); the toxoid platform in this question is one more member of the same taxonomy.
With reference to recent developments regarding 'Recombinant Vector Vaccines', consider the following statements: 1. Genetic engineering is applied in the development of these vaccines. 2. Bacteria and viruses are used as vectors. Which of the statements given above is/are correct?
- (a) 1 only
- (b) 2 only
- (c) Both 1 and 2
- (d) Neither 1 nor 2
Answer(c) Both 1 and 2
Same theme — vaccine-technology platforms (here recombinant/vector vaccines), the counterpart concept to the toxoid platform tested for diphtheria.
- practice — not a real PYQ
Besides diphtheria, which disease's vaccine is also a toxoid?
- (a)Tetanus
- (b)Measles
- (c)Tuberculosis
- (d)Polio
Answer(a) Tetanus — like diphtheria, it is a toxin-mediated disease prevented by a toxoid.
- practice — not a real PYQ
The DPT vaccine protects against which set of diseases?
- (a)Diphtheria, Pertussis and Tetanus
- (b)Diphtheria, Polio and Typhoid
- (c)Dengue, Plague and Typhoid
- (d)Diphtheria, Pneumonia and Tuberculosis
Answer(a) Diphtheria, Pertussis (whooping cough) and Tetanus.