Sinovac given for Covid-19 is a

Question

UnlockIAS · Accepted Answer

Correct — D, Whole virus vaccine. Sinovac is the Beijing-based company Sinovac Biotech, and its Covid-19 product CoronaVac is made the oldest way there is: whole SARS-CoV-2 virus is grown in cell culture (Vero cells), then killed with beta-propiolactone so that it can no longer replicate, and the dead but structurally intact virus is combined with an aluminium hydroxide adjuvant. Because the entire killed virion is injected, the immune system sees every surface antigen the virus carries, not just the spike protein — that is what 'whole virus vaccine' means. This is the same traditional inactivated platform used by India's own Covaxin (BBV152, Bharat Biotech) and by Sinopharm's BBIBP-CorV, which is why the three are usually grouped together in comparison tables. Two small precisions worth carrying: 'whole virus' is the broader family that covers both live-attenuated and inactivated vaccines, and CoronaVac belongs to the inactivated half; and the adjuvant is needed precisely because a killed virus is less immunogenic than a live one.

Why the other options are wrong — (a) This platform uses a harmless carrier virus, engineered so it cannot multiply in the recipient, to deliver the gene for the coronavirus spike protein. The Covid vaccines built this way are Oxford–AstraZeneca (marketed in India as Covishield), Russia's Sputnik V and the Janssen single-dose vaccine — not CoronaVac. Sinovac delivers no genetic instruction at all; it delivers the killed virus itself.  (b) The mRNA platform injects lab-made messenger RNA in a lipid nanoparticle so that the recipient's own cells manufacture the spike protein. The two Covid vaccines of this kind are Pfizer–BioNTech's Comirnaty and Moderna's Spikevax. It was the newest of the Covid platforms and the one that required ultra-cold storage; CoronaVac, by contrast, is stable at ordinary refrigerator temperatures precisely because it is a conventional inactivated vaccine.  (c) A subunit vaccine contains only a selected piece of the pathogen — for Covid, the spike protein or its receptor-binding domain — manufactured separately and given with an adjuvant. Novavax (licensed in India as Covovax) and Biological E's Corbevax are the subunit examples. The whole point of the subunit approach is that no complete virus is present; CoronaVac contains the complete, killed virion.

Concept: Vaccines are classified by what is actually injected. Whole-organism vaccines use the entire pathogen, either weakened so it can no longer cause disease (live-attenuated: BCG, oral polio, measles) or killed outright (inactivated: injectable polio, hepatitis A, CoronaVac, Covaxin). Subunit vaccines use only a purified fragment such as a surface protein. Toxoid vaccines use an inactivated bacterial toxin. Viral-vector vaccines use an unrelated, non-replicating virus to carry a gene for the target antigen. Nucleic-acid vaccines — mRNA and DNA — deliver the genetic instruction directly and let the body build the antigen itself. The trade-offs run in a predictable direction: the older whole-virus platforms are cheap, need no exotic cold chain and provoke a broad response to many antigens, but they are slow to manufacture and usually need an adjuvant and booster doses, while the newer genetic platforms can be designed within weeks of a genome being published but demand far more sophisticated production and storage.

State PCS 2022 Q62 — Science & Technology PYQ with Answer

State PCS 2022 Q62 — Science & Technology PYQ with Answer