Public health

Question 1

What is Herd Immunity?

Answer 1

• Vaccination of a significant proportion of a population which results in less risk to individuals who have not developed immunity.
• it disrupts chain of infection

Question 2

what is the typical threshold for herd immunity?

Answer 2

80-95%

Question 3

What are the types of immunisation? (explain them)

Answer 3

• active
  (stimulating the immune system. e.g. from an infection or vaccine.)
  Takes several weeks to develop immunity.

-passive
(introduction of an antibody, only protected until the antibody is lost from circulation)
usually immediate

Question 4

What are the types of passive immunity?

Answer 4

natural passive immunity- passing from mother to foetus (placenta) or by breast milk

acquired passive immunity- serum from individuals, or antibody containing blood products.

Question 5

what is a live attenuated vaccine?

Answer 5

pathogen is live but is weakened, so will cause reduced virulence.
Attenuated- not able to cause disease but stimulate an immune response.

Question 6

What is a killed vaccine?

Answer 6

Grow pathogen, and inactivate it before it’s administration.
doesn’t have disease producing capability

Question 7

what is a subunit vaccine?

Answer 7

only contains part of the pathogen which is antigenic or necessary to elicit an immune response.
e.g. proteins or peptides

Question 8

what is a toxoid vaccine?

Answer 8

Bacterial toxin that is no longer active but retains the property of combining/stimulating the formation of antibodies.

Question 9

What is an adjuvant?

Answer 9

increases or modulates the immune response to a vaccine

Question 10

what is the role of an adjuvant?

Answer 10

• increases the size of an immunogen
• increasing the retention of an immunogen at the target site
• increases the influx of immune cells

Question 11

Where are adjuvants derived from?

Answer 11

• bacteria
• Immune cell signals
• inert material

Question 12

What are the advantages of a live attenuated vaccines

Answer 12

• stimulates a more robust immune response
• usually long term or life long (don’t use boosters)
• accurately imitates an infection
• fast immunity onset
• only need one or 2 doses?

Question 13

What are the disadvantages of a live attenuated vaccines

Answer 13

• have the potential to revert back to their virulent form
• can’t be used in immunocompromised patients
• difficult to store or transport

Question 14

What are the advantages of a killed vaccines?

Answer 14

• can be used in immunocompromised and high risk groups
• easier to store & transport
• can’t revert to it’s original form

Question 15

What are the disadvantages of a killed vaccines?

Answer 15

• immune response is short lived, will need boosters
• doesn’t provide an as strong immune response
• need to culture/kill pathogen so is a slow process

Question 16

What are the advantages of subunit vaccines?

Answer 16

• can’t revert back to the infectious disease
• can be used in immunocompromised
• easier to store and transport

Question 17

What are the disadvantages of subunit vaccines?

Answer 17

• reduced immunogenicity
• require boosters and adjuvants
• difficult to isolate the specific antigen

Question 18

What are the advantages of toxoid vaccines?

Answer 18

• can’t cause the disease itself

- can’t revert to virulent form

Question 19

What are the disadvantages of toxoid vaccines?

Answer 19

• require adjuvants
• require multiple doses (tolerance can develop)
• don’t produce a full immune response
• only used in diseases where a disease is caused by a toxin

Question 20

what is an mRNA vaccine?

Answer 20

it introduces a piece of mRNA that corresponds to a viral protein

Question 21

how does the astrazeneca vaccine work?

Answer 21

delivers genetic code of the spike protein to the body cells.

Question 22

how does an mRNA vaccine work? (Pfizer and Moderna)

Answer 22

• mRNA is wrapped in a vector that eases the delivery of the protein and prevents the breakdown via the host.
• mRNA vaccine allows the immune system to recognise these key spike proteins that are present on coronavirus membranes and therefore enables the production of antibodies.

Question 23

What are the advantages of a mRNA vaccines?

Answer 23

• can’t revert to virulent form
• stimulates cellular immunity and humoral immunity (because antigens are produced inside the cell)
• manufacturing is…
  fast and cheap

Question 24

What are the disadvantages of a mRNA vaccines?

Answer 24

• storage requirements (mRNA is fragile)
• risks of unknown affects (first of it’s kind)
• May elicit an unintended immune reaction
• workforce training