principles of immunisation

Question 1

what are the different types of immunity

Answer 1

immunity is either adaptive or inate

adaptive immunity can be active or passive

active immunity can be natural (infection or exposure) or passive (immunisation)

passive immunity can be natural (placental transfer of IgG or colostral transfer of IgA) or passive (immunoglobulin therapy or immune cells)

Question 2

advantages passive immunity

Answer 2

immediate protection quick fix

Question 3

disadvantages of passive immunity

Answer 3

• short term effect - no immunologcal memory - serum sickness - incoming antibody is recognised as a foreign antigen by the recipient resulting in anaphylaxis - graft vs host disease (cell grafts only) - incoming immune cells reject the recipient

Question 4

natural passive immunity example

Answer 4

maternal immunoglobulins can be transferred to the foetus or neonate naturally using a specialised mechanism involving the neonatal Fc receptors

Question 5

artificial passive immunity examples

Answer 5

snake or spider bites, scorpion or fish stings: passive infusion of antibody specific for the toxin. Hypogammaglobulinemia: 1y/2y infusion of gamma-globulins to reduce infection. Rabies immunoglobulin: post-exposure prophylaxis together with vaccination

Question 6

where can immunoglobulin be used for post-exposure prophylaxis

Answer 6

• Human normal immunoglobulin (HNIG): Hep A, measles, polio, rubella - Specific immunoglobulins: Hep B, rabies, tetanus, varicella-Zoster virus

Question 7

active immunity types

Answer 7

Natural - exposure/infection, artificial - vaccination

Question 8

what stimulates active immunity

Answer 8

• Antigen (whole organism or part of it) stimulates immune response

Question 9

what are some of the benefits of active immunity

Answer 9

• Long term immunity - may be lifelong - Immunological memory - No immediate effect, faster and better response to next antigenic encounter

Question 10

how is immunisation related to active immunity

Answer 10

The administration of antigenic material (a vaccine) to stimulate an individual’s immune system to develop adaptive immunity to a pathogen

Question 11

name 3 common diseases vaccinated against

Answer 11

measles, mumps and rubella MMR vaccine

Question 12

what are the 4 types of vaccines

Answer 12

killed whole organism, attenuated whole organism, subunit vaccines, toxoid vaccines

Question 13

what are killed whole organism vaccines

Answer 13

target organism (e.g. polio virus) is killed (must be completely killed in order to be effective and not cause disease) effective and relatively easy to manufacture booster shots likely to be required,

Question 14

what are attenuated whole organism vaccines

Answer 14

(mainly viruses): an avirulent strain of target organism is isolated can be very powerful and better than killed vaccines, stimulate natural infection, reversion back to virulent form is possible refrigeration required

Question 15

what is circulating vaccine derived polio virus

Answer 15

Acute paralysis derived from the vaccine-virus which genetically mutates into a form that can paralyse, occurs in seriously under-vaccinated populations where the excreted vaccine-virus can circulate for an extended period of time

Question 16

what are subunit vaccines

Answer 16

• Recombinant proteins - have the structure of the virus but no genetic material so they can’t infect ○ Generally very safe ○ Easy to standardise ○ Not very immunogenic w/o effective adjuvant ○ Need to understand how to generate immunity

Question 17

what are toxoid vaccines

Answer 17

• Toxin is treated with formalin - Toxoid retains antigenicity but has no toxic activity - Only induces immunity against the toxin not the organism that produces it - E.g. tetanus, diphtheria

Question 18

5 examples of live attenuated vaccines

Answer 18

• Tuberculosis - BCG - oral polio vaccine - measles - rotavirus - yellow fever

Question 19

2 examples of killed antigen vaccines (attenuated)

Answer 19

• whole cell pertussis - inactivated polio virus

Question 20

2 examples of toxoid vaccines

Answer 20

tetanus toxoid diphtheria toxoid

Question 21

4 examples of subunit vaccines

Answer 21

• acellular pertussis
• haemophilus influenzae type B
• pneumococcal
• hepatitis b

Question 22

temporary contraindications of vaccination

Answer 22

febrile illness, pregnancy - can’t be given live attenuated vaccine as it could cause problems in the foetus

Question 23

permanent contraindications of vaccination

Answer 23

allergy, immunocompromised - can’t be given live attenuated vaccines as the individual may develop the disease from the vaccine strain

Question 24

what is herd immunity

Answer 24

• 1y aim of vaccination is to protect the individual who receives the vaccination - Vaccinated individuals are less likely to be a source of infection to others which reduces the risk of unvaccinated individuals being exposed to infection - Individuals who can’t be vaccinated will still benefit from routine vaccination programmes - 95% coverage is ideal as this prevents spread of infection

Question 25

what are 4 properties of a good vaccine

Answer 25

- Potent antibody response - high antibody titers - Potent CD8+ cytotoxic T cell response - CD4+ T helper response Memory

Question 26

what are the challenges facing vaccines

Answer 26

- Persistence - ideally vaccines should give life long protection - Generation of memory cells - Protection of vulnerable groups: young, elderly and immunocompromised - Antigenic shift and drift, strain diversity: bird and swine influenza pandemics - The cold chain network

Question 27

what is antigenic shift

Answer 27

2 or more different strains of a virus OR a strain of 2 or more different viruses combine to form a new subtype having a mixture of the surface antigens of the original strains it is a major change and can lead to epidemics

Question 28

what is antigenic drift

Answer 28

small changes in the proteins produced by the virus, minor changes from year to year, they arise from point mutations

Question 29

what is the cold chain network

Answer 29

- Purpose of the vaccine cold chain is to maintain product quality from the time of manufacture until the point of administration by ensuring vaccines are stored and transported within WHO recommended temp ranges Important to maintain the viability of the vaccine

Question 30

what are the challenges regarding neonates and vaccination

Answer 30

- Vulnerability \<18-24 mths to encapsulated bacteria e.g. pneumococcus, Hib and meningococcus - Fewer FDC and B cells don’t express costimulatory molecules - Short term antibody production

Question 31

what are the challenges regarding the elderly and vaccination

Answer 31

- Reduced efficacy or responsiveness to vaccination - Oligoclonal responses lacking specificity Reduced plasma cell several niches in the bone marrow

Question 32

what are conjugate vaccines

Answer 32

- Antigen is the carbohydrate capsule - Carbs are poor antigens (don’t stimulate the immune system as broadly as protein antigens), esp in babies - Conjugation of the carb to a protein carrier makes them more effective (generates a much more powerful immune response) - E.g. Streptococcus pneumoniae, Haemophilus influenzae type b, Neisseria meningitidis C

Question 33

HPV as a vaccine for cancer

Answer 33

- Cervical cancer is the 2nd most common cause of female cancer death - HPV linked to 100% of all cervical cancers (has also been linked to head and neck cancers) - Complete protection against \>70% of cancer causing HPV strains Currently 3 vaccines are available - protect against different numbers of strains

Question 34

checkpoint inhibitors

Answer 34

- Checkpoint inhibitor antibodies unlock the gateway to the adaptive immune system - Boosts the immune resopnse - Powerful anti-tumour responses - Potential for immune related adverse effects - Immunotherapy is a type of cancer treatment that helps your immune system fight cancer.

Question 35

example of herd immunity

Answer 35

babies \< 2mths who are too young to be immunised but are at the greatest risk of drying from whooping cough, they were felt to be protected because older siblings and other children have been immunised and so wouldn’t pass on the infection

Question 36

what is meant by high antibody titers

Answer 36

(how much antibody an organism has produced that recognises a particular epitope - the part of an antigen molecule to which an antibody attaches itself