The immunisation programme and how vaccines are made

Prelims and MainsCurrent affairs on this: Vaccines and immunisation

A vaccine shows the immune system a harmless version or piece of a pathogen so it makes antibodies and memory cells before the real infection. The platforms differ in what is shown. A live attenuated vaccine is a weakened pathogen (BCG, measles, oral polio); an inactivated one is a killed pathogen (injectable polio, rabies); a subunit or conjugate vaccine is one protein or sugar, sometimes joined to a carrier so infants respond (hepatitis B, pneumococcal, HPV); a toxoid is a disabled toxin (tetanus, diphtheria); a viral vector carries the gene for a pathogen protein inside a harmless virus (Covishield); an mRNA vaccine delivers the gene itself in a lipid particle. India's Universal Immunisation Programme, since 1985, gives free vaccines against twelve diseases through the public system, with Mission Indradhanush since 2014 to reach children missed, and U WIN since 2024 as the digital record of every dose.

Vaccine platforms

	Live attenuated	Inactivated	Subunit or conjugate	Toxoid	Viral vector	mRNA
What is given	weakened live pathogen	killed pathogen	one protein or sugar, with a carrier for infants	disabled toxin	harmless virus carrying a gene	the gene as mRNA in a lipid particle
Examples	BCG, measles and rubella, oral polio, rotavirus	injectable polio, rabies, Covaxin	hepatitis B, pneumococcal, HPV, pentavalent	tetanus, diphtheria	Covishield	Gemcovac and the Covid mRNA vaccines abroad
Strength	strong, long immunity, often one or two doses	safe for the immunocompromised	very safe, targeted	safe	strong cellular response	fastest to design
Weakness	not for the immunocompromised or in pregnancy; cold chain	weaker, needs boosters	needs adjuvant and boosters	only for toxin diseases	immunity to the vector	very cold storage, cost

The platforms trade strength of response against safety and speed; the programme is built on the first four, and the pandemic added the last two.Source: Standard immunology; Universal Immunisation Programme schedule

The twelve diseases of the Universal Immunisation Programme: tuberculosis (BCG), polio (oral and injectable), diphtheria, pertussis, tetanus, hepatitis B and Haemophilus influenzae type b (pentavalent), rotavirus, pneumococcal disease, measles and rubella, and Japanese encephalitis in endemic districts.
Herd immunity: when enough of a population is immune, transmission stops even for the unvaccinated; the threshold depends on how infectious the disease is, about 95 per cent for measles.
India's milestones: polio free since 2014 (last case 2011), maternal and neonatal tetanus eliminated in 2015, measles and rubella elimination targeted; the cold chain, from national stores to ice lined refrigerators at health centres, is the constraint in the last mile.
Adult and campaign vaccines outside the routine schedule: HPV against cervical cancer, typhoid conjugate, and the Covid vaccines, which brought the viral vector, mRNA, DNA (ZyCoV D, the first DNA vaccine licensed anywhere) and protein subunit (Corbevax) platforms into Indian production.
The Coalition for Epidemic Preparedness Innovations and Gavi are the international funders; India is both a Gavi recipient in transition and its largest supplier through the Serum Institute and Bharat Biotech.

Mains: India's immunisation success is logistics more than science: the vaccines are old and cheap, and the gains come from finding the child who was missed, which is what Indradhanush and U WIN exist to do.

UPSC has asked

Mains 2022: how vaccines work and the platforms Indian manufacturers used for Covid
Prelims 2021: how recombinant vector vaccines are made
Prelims 2016: what Mission Indradhanush is for

Further reading: Vaccines and immunization (WHO)