Immunisations

Question 1

What is passive immunity?

Answer 1

• Antibodies are passed onto but not made by the body
• body does not have template to make the antibody
• cannot make antibody again if needed
• once circulating antibodies disappear, no more immunity will be conferred

Question 2

What is active immunity?

Answer 2

• antibodies are made by the body
• body has the template to make antibody (memory)
• can make new antibodies if needed
• protected for life

Question 3

What is naturally acquired immunity

Answer 3

• come into contact with pathogen normally
• naturally acquired passive immunity, e.g. breast milk antibodies
• naturally acquired active immunity, e.g. catching chicken pox and being immune for life

Question 4

What is artifically acquired immunity?

Answer 4

• needs outside intervention
• artificially aquired passive immunity, e.g. injection with antibodies
• artificially acquired active immunity, e.g. vaccines

Question 5

What is immunisation?

Answer 5

• the process of making a person or animal immune to infections, typically by inoculation
• safe and effective way of protecting susceptible hosts

Question 6

How does immunisation work?

Answer 6

• deliver something resembling infectious agent (but not harmful) into the body
• trick the body into activating 3rd line defence
• t-lymphocytes (cell mediated)
• b-lymphocytes; make IgM first followed by memory antibody IgG
• therefore when the real pathogen enters the body, IgG will recognise and neutralise it before the person becomes sick

Question 7

What is herd immunity?

Answer 7

• if the majority of the population is vaccinated, then the disease will not spread easily; indirect protection
• those that are not immunised will benefit from herd immunity
• ~85% immunisation = coverage, but depends on disease
• protecting too young, those with immunosuppression, allergies, etc

Question 8

What must a vaccine be in order to be effective?

Answer 8

• protective
• safe
• lasts
• practical

Question 9

What is live attenuated vaccine?

Answer 9

• weakened live MO
• can grow but not cause damage
• response virtually identical to natural infection
• usually just need one dose, unless oral
• both antibody and T cell involved - strong immunity
• e.g. measles, mumps, rubella, varicella, oral polio
• potential problems; may revert to ‘wild type’ - wake up from coma

Question 10

What is an inactivated vaccine?

Answer 10

• whole MO, dead (or very badly injured)
• some may use the ‘business’ part of the MO
• require multiple doses
• first ‘primes’ immune system
• next = develop protective response
• mistly antibody, so wanes over time

Question 11

What is a pollysaccharide vaccine?

Answer 11

• ‘inactivated subunit’
• ID markers of the bug (antigens)
• work better if conjugated; a poor antigen is attached to a strong antigen, elicits a T-cell response
• e.g. HiB, meningococcal disease

Question 12

What is a recombient vaccine?

Answer 12

• genetically engineered
• grow just the ‘ID marker’ that is recognised
• e.g HBV, HPV