Vaccines

Question 1

What is a vaccine?

Answer 1

Any preparation which acts to induce or confer artificial immunity to a disease or substance

Question 2

Why do we create vaccines

Answer 2

1. Control: Reduction of disease morbidity or mortality in a defined area
2. Eliminate: A reduction in the incidence of disease or specific infection to 0 in an area
3. Eradication: Reduction of the world incidence to 0 so that deliberate intervention is no longer required

Question 3

How do we assess if the vaccine works

Answer 3

1. Immunogenicity: Does the vaccine elicit an immune response
2. Efficacy: Under ideal situations with ideal laboratory monitoring, does the vaccine work (clinical trial)

3.Effectiveness

Question 4

list the types of vaccines and their functions

Answer 4

1. Prophylactic :Aims to protect you against infection. Often requires the presence of neutralizing antibodies
   * Need to know the site of infection
2. Therapeutic: Aims to harness the immune system to fight against infection or cancer which is already present.
3. Live attenuated vaccines eg polio
4. Subunit vaccines: contains only specific antigens eg hepatitis B
5. Killed/inactivated vaccines : inactivated polio
6. Toxoid vaccines: contains only toxins eg tetanus
7. Conjugated vaccines: when the bug has a thick polypeptide coat eg H.influenc

Question 5

T/F: Killed / inactivated vaccines can result in herd immunity

Answer 5

false, live attenuated vaccines can result in herd immunity

Question 6

T/F: Polio results in chronic flaccid immunity

Answer 6

false, polio results in acute flaccid immunity

Question 7

Compare the advantages and disadvantages of polio vaccine

Answer 7

> Advantages

• Allows for herd immunity especially where there is resistance to vaccination
• Gives the best protection against natural infection

2>Disadvantages

• Can always revert to wild type
• Can give rise to vaccine-associated paralytic poliomyelitis
• can result in catastrophic infection in immunocompromised patients

Question 8

What are the pro and cons of subunit vaccines

Answer 8

pro:
*it is safe and stable
Cons: it is less immunogenic than a live vaccine and does not result in herd immunity

Question 9

What are the pros and cons of a conjugated vaccine

Answer 9

Pros: Can elicit responses even in babies and it is safe

Cons: Extremely expensive and may not elicit a perfect immunological responses

Question 10

MOA of DNA vaccines

Answer 10

> To improve a intracellular pathogen response ,you need to ensure that peptides are presented effectively

> This presentation needs to occur through MHC1 or stimulate TH1 response

> The idea with a dna vaccine is to ensure that viral associated peptides are transcribed as part of cellular response