Vaccinations

Question 1

Define vaccination

Answer 1

• preparation of antigenic material used to induce immunity against pathogenic organisms
• dead/attenuated form of pathogen

Question 2

Define passive immunity

Answer 2

• immunisation
• conferred by the transfer of preformed antibodies rather than by active production of antibodies after exposure to antigen

Question 3

Define active immunity

Answer 3

• induced by natural exposure to a pathogen or by vaccination

Question 4

What are the 4 kinds of immunity and how are they acquired ?

Answer 4

• natural active = natural infection
• artificial active = vaccination
• natural passive = transfer of antibody from mother to infant
• natural active = passive antibody therapy

Question 5

What are some uses of passive immunisation ?

Answer 5

• prevent infection in ‘ at risk’ individuals
• prevent infection post-exposure
• treatment of infection

Question 6

What are the different kinds of vaccine ?

Answer 6

• live attenuated
• inactive/killed
• subunit
• recominbant/DNA
• mRNA
• Toxoids

Question 7

Describe live vaccines

Answer 7

• Vaccinia originally used to protect against smallpox
• attenuated, non-pathogenic organism

Question 8

What are some of the problems with live vaccines

Answer 8

• induction of anti-viral state
• ineffective when given with antibody
• reversion to virulence
• contraindicated in immunosuppression
• potential for secondary spread

Question 9

Describe inactivated vaccines

Answer 9

• inactivation is achieved via heat, phenol or formalin
• poor immuogens due to altered immunogenicity - alum used as adjuvant

Question 10

What is Alum ?

Answer 10

• double salt of aluminium, or potassium aluminium sulfate

Question 11

What is adjuvant ?

Answer 11

• a substance inducing immune response which enhances the body’s response to an antigen/immunogen administered

Question 12

Describe Subunit vaccines

Answer 12

• induce immunity against surface proteins or those involved in invasion
• example = surface antigens - typhoid

Question 13

What are some drawbacks of subunit vaccinations ?

Answer 13

• many are poor immunogens which require adjuvants
• ,multiple serotypes of many infections = not protective against all
  -predominantly antibody response which is less effective against intracellular organisms

Question 14

Describe Recombinant/DNA vaccines

Answer 14

• traditionally more difficult to produce
• examples = Hep B vaccine & rabies vaccine for wildlife

Question 15

Describe mRNA vaccines

Answer 15

• delivered into hot cells via lipid nanoparticles
• mRNA translated in the human cell into spike protein
• host cell expresses viral spike proteins on the surface

Question 16

Describe toxoids

Answer 16

• altered bacterial toxins
• immunogenicity is maintained
• lose toxicity
• examples = diphtheria & tetanus toxoid
• used for routine protection & post-exposure prophylaxis

Question 17

What can cause adverse effects of immunisations

Answer 17

• immunogens
• other constituents in vaccine = eggs, antibiotics, adjuvants

Question 18

What are some local adverse effects of immunisation ?

Answer 18

• erythema (redness)
• pain
• pruritus (itching)

Question 19

What are some systemic adverse effects of immunisations ?

Answer 19

fever & anaphylaxis

Question 20

Define herd immunity

Answer 20

• when the majority of a population is immune to a pathogen, the chances of a susceptible individual contacting an infected individual is low