SN6 SHORT NOTE 5M ★ High-yield

Classify vaccines. Describe immunisation in India and passive immunisation.

Pharmacology · 2nd Professional — Para-Clinical

Classification of Vaccines

Type	Examples	Features
Live attenuated	BCG, oral polio (OPV), measles-mumps-rubella, varicella, rotavirus, yellow fever, typhoid Ty21a	Strong and long-lasting immunity, often after one dose; but contraindicated in pregnancy and immunosuppression, and they require a cold chain
Killed / inactivated	Injectable polio (IPV), rabies, hepatitis A, influenza, whole-cell pertussis, cholera	Safe in immunosuppression; weaker, so boosters and adjuvants are needed
Subunit / toxoid	Hepatitis B (recombinant surface antigen), tetanus and diphtheria toxoids, acellular pertussis, HPV	Very safe; require boosters
Conjugate	Haemophilus influenzae b, pneumococcal, meningococcal	A polysaccharide linked to a protein carrier, which converts a T-independent response into a T-dependent one — this is what makes them work in infants under 2, in whom plain polysaccharide vaccines fail
MRNA and viral vector	COVID-19 vaccines	Rapid development; the platform can be adapted to a new pathogen quickly

CLINICAL PEARL

Conjugation solved a problem specific to infants. Plain polysaccharide antigens provoke a T-cell-independent response, which the immature infant immune system mounts poorly and without memory. Linking the polysaccharide to a protein carrier recruits T-cell help, producing memory and a boostable response — and it also reduces nasopharyngeal carriage, so vaccinated children stop transmitting and herd immunity protects those too young to be vaccinated.

Immunisation in India

The Universal Immunisation Programme provides BCG, hepatitis B, oral and injectable polio, pentavalent (DPT with hepatitis B and Hib), rotavirus, pneumococcal conjugate, measles-rubella, JE in endemic districts, and DPT and TT boosters, free of charge
Mission indradhanush targets children and pregnant women who have been missed, and has substantially raised full immunisation coverage
India was certified polio-free in 2014, an achievement resting on mass campaigns, surveillance and social mobilisation rather than on any new vaccine
The cold chain is the practical limiting factor — most vaccines are damaged by heat, and some (OPV) by freezing; vaccine vial monitors indicate cumulative heat exposure
Adverse events following immunisation (AEFI) must be reported and investigated; distinguishing a genuine vaccine reaction from a coincidental event or a programme error (wrong diluent, unsterile injection) is essential, since a mishandled investigation damages public confidence far beyond the individual case

Passive Immunisation and Immunomodulators

Agent	Use
Immunoglobulins — specific	Tetanus, rabies, hepatitis B, varicella-zoster, anti-D — give immediate but temporary protection, and are used with the vaccine in post-exposure prophylaxis
Normal immunoglobulin (IVIg)	Primary immunodeficiency; immune thrombocytopenia, Guillain-Barré syndrome, Kawasaki disease
Antivenom, antitoxin	Snake envenomation, diphtheria, botulism
Interferons	Interferon-alpha in hepatitis B and some malignancies; beta in multiple sclerosis
Immunostimulants	BCG instillation in superficial bladder cancer; levamisole; colony-stimulating factors
Immunosuppressants	Calcineurin inhibitors, corticosteroids, azathioprine, mycophenolate, biologicals — transplantation and autoimmune disease

Applied Aspects

Live vaccines are contraindicated in pregnancy and significant immunosuppression, and should be given at least 4 weeks before planned immunosuppression or 3 months after stopping it
Vaccinate before immunosuppression wherever possible — before transplantation, splenectomy, biological therapy or chemotherapy
Minor illness is not a contraindication; deferring immunisation for a coryza is a major cause of missed opportunity, and the child may not return
Rabies post-exposure prophylaxis — thorough wound washing with soap and water for 15 minutes, vaccine, and immunoglobulin infiltrated into the wound for category III exposure. India has a large rabies burden and the disease is invariably fatal once established, yet entirely preventable
Address vaccine hesitancy with respect and evidence; dismissing concerns entrenches them, and trust in the vaccinator is what determines uptake
Anaphylaxis after vaccination is rare but must be prepared for — adrenaline available, and observation for 15 to 30 minutes afterwards

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