T3-L10: Immunisation

Question 1

What is active immunisation?

Answer 1

Active immunity is usually long-lasting immunity produced by the immune system in response to antigens.
These antigens can be from natural infection or from vaccination.

The benefit of vaccination is that active immunity occurs without disease or disease complications.
The persistence of protection for many years after natural infection or vaccination is called “immunologic memory.”

Question 2

What is passive immunisation?

Answer 2

Passive immunity is provided when a person is given antibodies to a disease rather than producing them through his or her own immune system. This type of passive immunity, although effective, usually disappears within several weeks or months.

Example: Transfer from mother to unborn baby
“Maternal antibodies” can protect the baby for up to a year against illnesses to which the mother is immune.

Question 3

What agents are available for passive immunisation?

Answer 3

• Vertical transmission of auto-antibodies from mother to foetus & breastfeeding
• Injection of human immunoglobulin
  HNIG – pooled plasma
  Specific – tetanus, botulism, hep B, rabies, varicella

Question 4

What agents are used for active immunity?

Answer 4

• Inactivated or attenuated live organisms e.g. diphtheria, tetanus (organisms) and diphtheria, tetanus (toxins)
• Live: MMR, BCG, Yellow fever, Varicella
• Components of organisms e.g. influenza, pneumococcal
  Inactivated toxins

This act like the natural infection.

Question 5

What do we test to see if an individual has immunological memory?

Answer 5

IgG antibodies

Question 6

What are advantages of using live vaccines?

Answer 6

• Single dose often sufficient to induce long-lasting immunity
• Strong immune response evoked
• Local and systemic immunity produced

Question 7

What are disadvantages of using live vaccines?

Answer 7

• Potential to revert to virulence
• Contraindicated in immunosuppressed patients and also in pregnancy e.g. the MMR vaccine
• Interference by viruses or vaccines and passive antibody
• Poor stability
• Potential for contamination

Question 8

What are advantages of using inactivated vaccines?

Answer 8

• Stable
• Constituents clearly defined
• Unable to cause the infection

Question 9

What are disadvantages of using inactivated vaccines?

Answer 9

• Need several doses
• Local reactions common
• Adjuvant needed
• Shorter lasting immunity