W11 - Bacterial & viral vaccines

Question 1

1st event of vaccination

Answer 1

Benjamin Jesty - vaccinated his wife and 2 children against smallpox (1774)

Edward Jenner - scraped pus from cowpox lesion and scratched it into the arm of a 13 year old boy (1796)

Question 2

Describe what R(0) [R knot] is? At what R(0) is transmission halted?

Answer 2

The number of people that ONE SICK PERSON will infect (ON AVERAGE) is called R(0).

If effective R(o) is reduced to less than 1, transmission is halted!

Question 3

What virus has the highest R(0)?

Answer 3

Measles => R(0) = 18

Question 4

Describe Herd Immunity.

What is the Herd Immunity Threshold formula

Answer 4

Herd imunity = form of immunity that occur when vaccination of a significant portion of a population provides a measure of protection for individuals that are not immune.

HIT = 1-1/R(0)

Question 5

What is an important factor of immune response to attenuated virus vaccines?

Answer 5

T cell response is important in destroying the infected cell!

Question 6

Name the 8 types of vaccines we have?

Answer 6

1. Inactivated
2. Attenuated
3. Toxoid
4. Subunit
5. Conjugate vaccine
6. Heterotypic
7. Viral vectored
8. Nucleic acid

Question 7

Advantages + disadvantages of inactivated vaccines

Answer 7

Advantages:

1) stable
2) constituents clearly defined
3. Unable to cause infection

Disadvantages:

1. Need several doses
2. Local reactions common
3. Adjuvant needed
4. Shorter lasting immunity

Question 8

What are attenuated vaccines?

Give 4 examples

Answer 8

1. Measles
2. Mumps
3. Rubella
4. Yellow fever

Question 9

What are toxoid vaccines?

Give 2 examples

Answer 9

Inactivated toxic components

1. Tetanus
2. Diphtheria

Question 10

What are subunit vaccines

Give 2 examples

Answer 10

Subunit vaccines contain a protein component of the microorganisms or synthetic virus-like particles, lack viral gentic material and hence are unable to replicate

• Hepatitis B
• HPV

Question 11

What are conjugate vaccines?

Give 1 example

Answer 11

Conjugate vaccines are those with a poorly immunogenic antigen that is paired with a protei that is higly immunogenic (adjuvant)

• Haemophilus influenza type B

Question 12

What are heterotypic vaccines?

Give 1 example

Answer 12

Heterotypic vaccines are those with pathogens that infect other animals but do not cause disease or cause MILD disease in humans

• BCG

Question 13

What are viral vectored vacines?

Give 3 examples

Answer 13

viral vectored vaccines use a modified virus (i.e. adenovirus) to deliver genetic code for an antigen

1. Ebola
2. Janssen COVID vaccine
3. AZ COVID vaccine

Question 14

What are nucleic acid vaccines?

Give 2 examples

Answer 14

Nucleic acid vaccines use DNA/RNA from the pathogen

1. Pfizer COVID vaccine
2. Moderna COVID vaccine

Question 15

What are monovalent vs multivalent vaccines?

Answer 15

A monovalent vaccine contains a single strain of a single antigen (e.g. Measles vaccine), whereas a polyvalent vaccine contains two or more strains/serotypes of the same antigen (e.g. OPV).

Question 16

What are 2 barriers to vaccination?

Answer 16

1. Access!
2. Anti-vaccination

Question 17

What are 5 prerequisites for successful disease eradication?

Answer 17

1. No animal reservoir
2. Antigenetically stable pathogen with 1 (or a few) strains
3. No latent reservoir of infection + no integration of pathogen genetic material into host genome
4. Vaccine must induce lasting + effective immune response
5. High coverage requird for very contagious pathogens

Question 18

In terms of the COVID vaccines, what are the serious side effects of:

• adenoviral vectored vaccines (i.e. AZ)
• Pfizer vaccine

Answer 18

• adenoviral vectored vaccines (i.e. AZ) = VITT (vaccine-induced thrombotic thrombocytopaenia), Capillary leak syndrome (CLS)
• Pfizer vaccine = lymphadenopathy, myocarditis