Lecture 3 - Part 1: Vaccines Flashcards
What are the benefits of vaccination?
- Decrease mortality
- Decrease morbidity
- Decrease transmission
- Decrease in the disruption of one’s daily life
- Reduction in medical and other costs
- Improves quality of life overall
Give a brief history of vaccines.
- Smallpox was an ancient but serious infectious disease
- Throughout history, various civilizations tried to prevent and control the disease which eventually led to the development of vaccines
Define variolation (in terms of smallpox).
The process of exposing an individual with smallpox material
How did different countries attempt variolation/inoculation?
- China: dry scabs under the sun and inhale
- India: lance the pustule and transfer it to the arm of a healthy individual
Who was Edward Jenner/what did he do?
- Father of immunology
- May 1796: inoculated an 8-year-old boy with cowpox
- July 1796: inoculated him with smallpox and no disease developed
- Named it vaccination
- Note: there is cross-reactivity between these viruses
Define vaccine.
A biological product that can be used to safely induce an immune response that confers protection against infection/disease on subsequent exposure to a pathogen
A vaccine must contain _____.
antigens that the immune system can recognize on a pathogen or toxin.
List common vaccine components.
- Active ingredients
- Adjuvants
- Antibiotics
- Stabilizers
- Preservatives
- Trace components
What are the 2 main immune responses?
- Innate
- Adaptive
Describe the innate immune response.
- First line of defense
- Not specific
- Eliminate the invader
- Prevent spread and movement of pathogens
- Initiate the adaptive immune response
Describe the adaptive immune response.
- More effective in eliminating the pathogen
- Results in immunological memory
- Cell-mediated and antibody-mediated immunity
Describe cell-mediated immunity.
- Effective for intracellular pathogens
- Cytotoxic T-cells kill infected cells
Describe antibody-mediated immunity.
- Effective for extracellular pathogens
- Neutralization and increase phagocytosis
The primary response after initial exposure is _____ and requires the _____ immune system to control the infection until the _____ immune response kicks in.
- slow
- innate
- adaptive
How are vaccines categorized?
- Whole cell/virus or component based
- Alive (attenuated) or not alive (inactivated)
Explain live attenuated vaccines.
- Use pathogens that have reduced virulence and don’t cause disease
- Most common type
- Still induces an immune response
How is attenuation achieved?
By serial passages of virus largely through non-human cells
What are the pros and cons of live attenuated vaccines?
Pros
- More potent (activate cell-mediated response)
- Long-lasting protection
- Requires 1-2 doses
Cons
- Can cause severe disease in immunocompromised people
- Can’t be given to pregnant people
- Can revert to pathogenic form
- Temperature sensitive
Explain inactivated vaccines.
- Composed of killed pathogens that can’t replicate or cause disease
- Can be inactivated through physical and/or chemical methods
How are inactivated vaccines made?
- Chemical: formaldehyde
- Physical: heat, UV light, gamma radiation, pH
What are the pros and cons of inactivated vaccines?
Pros
- Generally safer
- Easier to transport
Cons
- Don’t activate cellular immune response
- Require 3+ doses for max immunity
- Protection fades over time
Explain subunit vaccines.
- Composed of specific antigens from the pathogen
- Types: recombinant protein/peptide, conjugate, toxoid
Describe conjugate vaccines.
Polysaccharides from bacterial capsules covalently attached to a protein antigen
Describe toxoid vaccines.
Chemically inactivated bacterial toxins
What are the pros and cons of subunit vaccines?
Pros
- Less adverse reactions
- Target toxins and bacterial capsules
Cons
- Don’t activate cellular immune response
- Require 3+ doses for max immunity
- Protection fades over time
Explain mRNA vaccines.
Synthetic mRNA in which ribosomes in the host recognize and translate the antigen (spike protein)
What are the pros and cons of mRNA vaccines?
Pros
- Effective
- Safe
- Can be modified quickly
Cons
- Must be kept frozen
- New
What is the function of adjuvants in vaccines?
Enhances that immunogenicity of vaccines
What is the function of antibiotics in vaccines?
Prevent contamination during manufacturing
What is the function of preservatives in vaccines?
Prevents microbial growth
What is the function of stabilizers in vaccines?
Protect the active ingredient during manufacturing, storage, and transport
Describe adverse reactions.
- Allergic reactions
- Local and systemic adverse reactions
