Bacterial and Viral Vaccines Flashcards

1
Q

What is R0?

A

The number of people one sick person will infect on average.

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2
Q

What is the R0 of hepatitis?

A

2

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3
Q

What is the R0 of ebola?

A

2

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4
Q

What is the R0 of HIV?

A

4

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5
Q

What is the R0 of SARS?

A

4

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6
Q

What is the R0 of mumps?

A

10

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7
Q

What is the R0 of measles?

A

18

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8
Q

What is herd immunity?

A

Form of immunity that occurs when vaccination of a significant proportion of a population provides a measure of protection for individuals that are not immune.

Herd Immunity Threshold is the percentage of fully immune individuals required to stop the spread of disease.

HIT = 1 -1/R0

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9
Q

How do vaccines trigger the immune response?

A

Antigen Presenting Cells present part of the antigen on the cell surface.

APCs present antigens to naïve T cells (in lymph nodes) which are activated.

Activation of B cells in response to antigens (+/- APCs).

Proportion of activated B cells will mature into plasma cells.

Plasma cells produce antibodies specific for the vaccine antigen.

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10
Q

How do antibodies and T cells neutralise pathogen activity?

A

Antibodies bind to specific antigen:

  • Neutralization of infectivity
  • Antibody dependent cellular cytotoxicity

If attenuated virus vaccine, then T cell response important in destroying infected cells.

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11
Q

What is the goal of vaccination?

A

Goal of vaccination is to produce memory cells to the vaccine antigen.

Response to pathogen post vaccination is increased and more antibodies are produced.

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12
Q

Why are vaccines less effective in elderly people?

A

Decreased resevoir of naive T-cells.

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13
Q

What are inactivated vaccines?

A

Whole microorganism destroyed by heat, chemicals, radiation or antibiotics (e.g. Influenza, cholera, polio).

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14
Q

What are the advantages of inactivated vaccines?

A

Stable

Constituents clearly defined

Unable to cause the infection

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15
Q

What are the disadvantages of inactivated vaccines?

A

Need several doses

Local reactions common

Adjuvant needed

Shorter lasting immunity

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16
Q

What are live attenuated vaccines?

A

Live organisms modified to be less virulent.

Examples: Measles, mumps, rubella, yellow fever

17
Q

What are toxoid vaccines?

A

Inactivated toxic components.

Examples: Tetanus, diphtheria

18
Q

What are subunit vaccines?

A

Protein component of the microorganisms or synthetic virus like particles. Lacking viral genetic material and unable to replicate.

Examples: Hepatitis B, HPV

19
Q

What are conjugate vaccines?

A

Poorly immunogenic antigens paired with a protein that is highly immunogenic (adjuvant).

Examples: Haemophilus influenzae type B

20
Q

What are heterotypic vaccines?

A

Pathogens that infect other animals but do not cause disease or cause mild disease in humans.

Example: BCG

21
Q

What are viral vectored vaccines?

A

Use a modified virus (e.g. adenovirus) to deliver genetic code for an antigen.

Examples: Ebola, Janssen and AZ COVID vaccines

22
Q

What are nucleic acid vaccines?

A

Use DNA/RNA from the pathogen.

Examples: Pfizer and Moderna COVID vaccines.

23
Q

What are the components of a vaccine?

A

Stablisers

Adjuvants: Increase immune response without decreasing specificity

Preservatives

Antibiotics: Used to manufacture but subsequently removed

Trace components

24
Q

What is the most common adjuvant used?

A

Aluminium hydroxide

25
Q

Which vaccines are contraindicated in HIV patients?

A

Yellow fever

BCG

NOT MMR

26
Q

How long should be left before primary doses of the same vaccine?

A

3 weeks to avoid competition

27
Q

What are prerequisites for success for disease elimination?

A
  • No animal reservoir
  • Antigenically stable pathogen with only one (or small number of) strains
  • No latent reservoir of infection and no integration of pathogen genetic material into host genome
  • Vaccine must induce a lasting and effective immune response
  • High coverage required for very contagious pathogens
28
Q

What are determinants of primary vaccine antibody response?

A

Vaccine type:

  • Live vs attenutated
  • Protein vs polysaccharide
  • Adjuvants

Antigen nature:

  • Polysaccharide agents
  • Protein antigens
  • Antigen dose

Vaccine schedule:

  • Interval between doses
  • Genetic determinants
  • Environmental factors
  • Age at immunisation
29
Q

What are determinants of duration of protection post immunisation?

A

Vaccine type:

  • Live vs attenuated
  • Polysaccharide antigens

Vaccine schedule:

  • Interval between primary doses
  • Interval between boosting
  • Age at immunisation
  • Environmental factors