BPSC 69th CCE Prelims General Studies · Question 18 of 144

Correct — C, By introducing a harmless piece of SARS-CoV-2 virus. Every COVID-19 vaccine used at scale works by showing the immune system one thing from the virus — the spike protein that studs its surface — or the genetic instructions for the body to build that protein itself. WHO's own explainer sorts vaccines into three families, and the COVID-19 vaccines occupy the second and third: those that use 'just the parts of the germ that triggers the immune system', and those that use 'just the genetic material that provides the instructions for making specific proteins and not the whole virus'. Trace India's four platforms and the pattern holds. Covishield, made by the Serum Institute of India, is the Oxford–AstraZeneca ChAdOx1 vaccine: a replication-deficient chimpanzee adenovirus, harmless in humans, carrying the SARS-CoV-2 spike gene as cargo. Corbevax and Novavax are protein-subunit vaccines — purified spike protein with an adjuvant, no virus present at all. ZyCoV-D from Zydus Cadila is a plasmid-DNA vaccine, the spike gene delivered intradermally by a needle-free jet injector in three doses. The mRNA vaccines wrap spike-coding messenger RNA in a lipid nanoparticle, and the cell reads it, builds the spike, and displays it. In none of these does a functioning SARS-CoV-2 enter the body. The immunology that follows is the same in each case: the spike acts as the antigen, the immune system makes antibodies against it and — the point of the whole exercise — leaves behind antibody-producing memory cells, so that a real infection later meets a response that is immediate rather than slow. One honest caveat: Covaxin, the Bharat Biotech and ICMR–National Institute of Virology vaccine, is a whole-virion inactivated vaccine, so it introduces the entire virus rather than a piece of it, but killed by chemical treatment and incapable of replicating. Even there, option (c) is the only defensible choice on this list, because (a), (b) and (d) each describe something a COVID-19 vaccine categorically is not.

• (a)By introducing live attenuated SARS-CoV-2 virus — This is a real vaccine platform, but not the one used against COVID-19. A live-attenuated vaccine contains a living but weakened version of the pathogen — the MMR, chickenpox, shingles and oral polio vaccines are the standard examples, and WHO notes they may be unsuitable for people whose immune systems are compromised. No live-attenuated SARS-CoV-2 vaccine was deployed in India's programme or in any of the major global rollouts. The trap is Covaxin, which is indeed a whole-virion vaccine and is therefore misremembered as 'live': it is inactivated, meaning the virus has been killed with chemicals so that it cannot replicate, which WHO treats as a separate category from live-attenuated.
• (b)By introducing a real SARS-CoV-2 virus — Deliberately giving someone a functioning pathogen is inoculation of the pre-Jennerian kind, not vaccination — it would risk causing the very disease the vaccine exists to prevent. WHO states the governing principle plainly: whatever a vaccine contains, 'this weakened version will not cause the disease in the person receiving the vaccine, but it will prompt their immune system to respond much as it would have on its first reaction to the actual pathogen'. Whole-virion COVID-19 vaccines such as Covaxin use virus that has been inactivated precisely so that it is no longer real in the sense this option means.
• (d)By introducing antibodies against SARS-CoV-2 virus — This describes passive immunisation, which is the opposite of what a vaccine does. Giving ready-made antibodies — monoclonal antibody cocktails, convalescent plasma, or the anti-tetanus and anti-rabies immunoglobulins — protects immediately but only for weeks, because the recipient's own immune system has done nothing and no memory cells are formed. A vaccine works the other way round: it supplies the antigen and makes the body manufacture its own antibodies and its own memory, which is why protection is slower to appear and far longer-lasting.

A vaccine's job is to teach the immune system a pathogen's face without letting the pathogen do any damage. WHO's account of the natural response sets the terms: a pathogen carries subparts unique to it, and the subpart that causes antibodies to be formed is called an antigen. On first exposure the body takes time to produce antigen-specific antibodies, and the person is vulnerable in the interval; once those antibodies exist they destroy the pathogen, and the body also creates antibody-producing memory cells that survive long after the infection is cleared, so a second encounter is met at once. A vaccine reproduces that first exposure using something safe. It may contain the antigen itself — a killed whole microbe, a weakened one, or an isolated protein subunit — or it may contain only the blueprint for the antigen, as DNA or messenger RNA, and let the recipient's own cells manufacture it. For SARS-CoV-2 the antigen chosen almost everywhere was the spike protein, the structure the virus uses to bind the ACE2 receptor and enter cells, which makes antibodies raised against it doubly useful: they mark the virus for destruction and they physically block the doorway.

The four options map onto four different biological transactions, and naming each one settles the question without any recall of brand names. Option (b) is infection. Option (a) is the live-attenuated platform — real, in wide use for measles and polio, but not used for COVID-19. Option (d) is passive immunisation, in which the antibodies arrive pre-made and the recipient's immune system never learns anything. Option (c) is active immunisation with an antigen, which is what vaccination means. Ask the single discriminating question — does the recipient's body end up making its own antibodies and its own memory cells? — and only (c) and (a) survive, after which the factual point that no live-attenuated SARS-CoV-2 vaccine was rolled out decides it. The word 'harmless' is doing real work in the correct option and is worth pausing on: what makes the vaccine safe is not that the piece is small but that it cannot replicate or cause disease. A spike protein on its own cannot assemble a virus; a chimpanzee adenovirus vector has had its replication genes removed; messenger RNA degrades within days and never enters the cell nucleus. Be aware, finally, of the one imperfect fit — Covaxin's inactivated whole virion is more than a piece — because BPSC and UPSC both like to test candidates on exactly that platform distinction.

• WHO's explainer of 12 January 2021 groups vaccines by whether they use a whole virus or bacterium, only the parts of the germ that trigger the immune system, or only the genetic material carrying instructions for making specific proteins. Inactivated vaccines kill the pathogen with chemicals, heat or radiation, as the flu and polio vaccines do; live-attenuated ones use a living but weakened form, as MMR and chickenpox do.
• India's four platforms: Covishield (Serum Institute of India) is the Oxford–AstraZeneca ChAdOx1 chimpanzee-adenovirus vector; Covaxin (BBV152, Bharat Biotech with ICMR–National Institute of Virology) is whole-virion inactivated; Corbevax is a protein-subunit vaccine; and ZyCoV-D (Zydus Cadila, supported by BIRAC) is a plasmid-DNA vaccine given intradermally in three doses by a needle-free jet injector.
• India's national vaccination drive began on 16 January 2021 and had delivered more than 2.2 billion doses by 4 March 2023, covering first, second and precautionary doses.
• ZyCoV-D was billed by its maker as the world's first plasmid-DNA vaccine against COVID-19, reporting interim efficacy of 66.6 per cent against symptomatic disease and 100 per cent against moderate or severe disease before receiving emergency-use authorisation in India in August 2021.
• Active versus passive immunity is the distinction the fourth option rests on: a vaccine gives an antigen and the body builds its own antibodies plus memory cells, giving slow-onset but durable protection, whereas monoclonal antibodies, convalescent plasma and anti-tetanus or anti-rabies immunoglobulin deliver antibodies directly for immediate but short-lived cover and leave no immunological memory.

• Calling Covaxin a live-attenuated vaccine: it is a whole-virion INACTIVATED vaccine, killed and unable to replicate, which is a different WHO category
• Calling Covishield an mRNA vaccine — a distractor UPSC used verbatim in 2022; Covishield is a chimpanzee-adenovirus viral-vector vaccine, and no mRNA vaccine was a mainstay of India's rollout
• Treating antibody therapy as vaccination: monoclonal antibodies and convalescent plasma give immediate but temporary protection and leave no memory cells, so they immunise passively rather than vaccinate

BPSC asks this at mechanism level in plain language — one line, four one-clause options, testing whether a candidate can tell an antigen from an antibody and a piece of a virus from the whole thing; the 69th paper puts a companion question on viral-vector vaccines only a few numbers later. UPSC asks the same material as brand-to-platform matching inside a statement set, as in 2022 when it paired Covishield with the mRNA platform to see who would notice, or through the underlying vocabulary — what an antigen is, how a recombinant vector vaccine is engineered.

• practice — not a real PYQ

  Which one of the following COVID-19 vaccines used in India is a whole-virion inactivated vaccine?

  • (a)Covishield
  • (b)Covaxin
  • (c)Corbevax
  • (d)ZyCoV-D

  Answer(b) Covaxin — BBV152, developed by Bharat Biotech with the ICMR–National Institute of Virology from whole SARS-CoV-2 killed by chemical inactivation; Covishield is a viral-vector vaccine, Corbevax a protein-subunit vaccine and ZyCoV-D a plasmid-DNA vaccine.

• practice — not a real PYQ

  Administering ready-made antibodies, such as anti-rabies immunoglobulin or a monoclonal antibody cocktail, to a patient is an example of

  • (a)active immunity
  • (b)passive immunity
  • (c)innate immunity
  • (d)herd immunity

  Answer(b) passive immunity — protection is immediate because the antibodies are supplied ready-made, but it is short-lived and generates no memory cells, unlike active immunity acquired from infection or vaccination.