MI: Bacterial and Viral Vaccines Flashcards
What R0 is required for a disease to be halted?
R0 < 1
R0 = number of people infected by one infectious person
What is herd immunity?
Form of immunity that occurs when vaccination of a significant proportion of the population provides a measure of protection for individuals that are not immune
What is the herd immunity threshold?
Threshold = 1 - 1/R0
What are the main immunological targets of vaccines?
Lymphocytes and antibody production
Which other response is important for live-attenuated vaccines?
T cell response to destroy infected cells
What are the three main types of memory cell?
- Memory B cells
- Memory killer T cells
- Memory T helper cells
What are protective antigens?
Microbial components that give rise to a protective immune response to future infection
What’s an inactivated vaccine?
Inactivated
- Whole organism is detroyed (using heat, radiation or antibiotics)
- NO risk of causing infection in the host
- Immune response may not be particularly strong or long-lasting
What’s a live attenuated vaccine
Live attenuated
- Live organisms are modified to be less virulent
- Risk of acquiring virulence
- Should be avoided in pregnant women and immunocompromised patients
- Eg. MMR
What’s a toxoid vaccine?
Toxoid
- Inactivated toxin components
- eg. Tetanus or Diptheria
What’s a subunit vaccine?
Subunit
- Protein components of the microorganisms or synthetic virus-like particles
- Lack genetic material and are unable to replicate
- eg. Hep B, HPV
What’s a conjugate vaccine?
Conjugate
- Poorly immunogenic antigens are paired with a protein that is highly immunogenic (adjuvant)
What’s a heterotypic vaccine?
Heterotypic
- Using pathogens that infect other animals but do NOT cause disease in humans
List some examples of the following types of vaccines:
- Inactivated
- Live attenuated
- Toxoid
- Subunit
- Conjugate
- Heterotypic
-
Inactivated
- Influenza
- Polio
- Cholera
-
Live attenuated
- MMR
- Yello fever
-
Toxoid
- Diphteria
- Tetanus
-
Subunit
- Hepatitis B
- HPV
-
Conjugate
- Haemophilus influenza type B
-
Heterotypic
- BCG
What are stabilisers?
Substances that are added to the vaccine to keep it chemicall stable