Principles of Immunisation

Question 1

Active immunisation

Answer 1

Occurs naturally via exposure or infection or artificially via vaccination. The whole or part of an antigen stimulates an immune response leading to long-term immunity as immunological memory is created. No immediate effect but faster response to next encounter.

Question 2

Passive immunity

Answer 2

Occurs naturally from mum to fetus or artificially via antivenom, IV immunoglobulin (IVIg) or rabies Ig. It provides immediate protection but creates no immunological memory. May lead to serum sickness of the body recognises the antibody as foreign.

Question 3

Vaccination

Answer 3

The administration of antigenic material to stimulate an individuals immune system to develop adaptive immunity to a pathogen.

Question 4

Inactivated vaccine

Answer 4

Killed whole organism. The virus must be effectively heat killed to prevent vaccine related disease. There is a target organism. They are effective and easy to manufacture but boosters are likely required. E.g. whole cell pertussis, inactivated Polio

Question 5

Attenuated whole organism vaccine

Answer 5

Live vaccine. Isolated avirulent strain of target organism. Very powerful and stimulate natural infection. Must be refrigerated and can revert back to virulent form. E.g. TB/BCG, measles, yellow fever.

Question 6

Subunit vaccines/purified antigen

Answer 6

Recombinant proteins, generally very safe and easy to standardise. Not very immunogenic without adjuvant. Boosters required. E.g. influenzae B, pneumococcal

Question 7

Toxoid

Answer 7

Toxin treated with formalin so it retains antigenicity but not toxic activity. It only induces immunity against toxin.

Question 8

Combinations

Answer 8

2+ vaccines mixed

Question 9

Immunotherapy

Answer 9

E.g. HPV

Question 10

Contra-indications to vaccination

Answer 10

Temporary; febrile illness, pregnancy.

Permanent; allergy, immunocompromised (live)

Question 11

Describe how an immune response occurs

Answer 11

Humoral

1. Recognition of foreign antigen and B cell activation
2. Clonal selection; division of activated B cells
3. Differentiation; plasma cells and memory B cells
4. Plasma cells produce antibodies that bind to the antigen.
5. Memory B cells retained for immunologic memory/ secondary response.

Question 12

Herd immunity

Answer 12

The vaccination of a significant portion of population provides a measure of protection for individuals who are not immune as vaccinated individuals are less likely to be a source of infection to others.

Question 13

Travellers vaccines

Answer 13

Hep A, Typhoid, N.Meningitidis serogroups A, C, W135, Y, Cholera, yellow fever, Japanese encephalitis, tick-borne encephalitis, rabies.