Updated: 11/20/2019

Immunization

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Introduction

  • Immunization allows for individuals to be protected against disease
  • Immunity can be conferred in two ways including
    • active immunity that is maintained by the immune system
    • passive immunity that is given transiently from outside
  • Vaccinations are a major source of conferring immunity outside normal infection and include
    • viral vaccines divided into
      • killed vaccines
      • live attenuated vaccines
    • bacterial vaccines
  • Often vaccinations require an adjuvent that
    • enhances the immune reaction against the vaccine provided
    • increases the development of memory to non inflammatory antigens
    • can be of several types including
      • aluminum potassium sulfate
      • muramyl dipeptide
      • LPS/polyribonucleotides
  • Though vaccines are generally safe, contraindications to their use include
    • people with egg allergies who should avoid 
      • yellow fever vaccine and other vaccines made in eggs
    • pregnant women who should avoid 
      • rubella vaccines
    • immunocompromised individuals who should avoid
      • all live vaccines
Active vs Passive Immunity
  • Immunity can be either active or passive with several notable differences
Differences Between Active and Passive Immunity
Feature Passive
Active
Acquisition method
  • Receiving preformed antibodies
  • Exposure to infection or to foreign antigens
Examples
  • Maternal IgG crossing placenta
  • Babies getting IgA in breast milk
  • Administration of antitoxin
  • Infection with the specific pathogen
  • Administration of a vaccine
Onset
  • Immediate upon administration
  • Slow to allow for development of full immune response     
Duration
  • Very short with a half life between two weeks and four weeks
  • Long or even lifetime
  • Due to generation of memory
 
Viral Vaccines
  • Viral vaccines can either be live attenuated or killed with several notable differences

Differences between Live and Killed Vaccines

Feature Live
Killed
Production method
  • Design a nonpathogenic version of a virus that can still grow transiently in the host
  • Inactive pathogen or pathogen antigens by treatment with heat or chemicals
Pros
  • Induce both cellular and humoral responses
  • induces lifelong immunity (usually)
  • Safer than live vaccines because they cannot revert to pathogenic state
Cons
  • Cannot give to immunocompromised patients
  • Small chance of reverting to pathogenic state
  • Weaker response (usually only humoral)
  • May require booster shots     
Examples
  • Everything else
  • MMR
  • VZV
  • Polio (Sabin)
  • Etc
  • Rest In Peace Always 
  • Rabies
  • Influenza
  • Polio (Salk)
  • Hepatitis A
Bacterial Vaccination
  • Bacterial vaccination involves administration of characteristic protein which can be
    • inactivated toxin produced by pathogen called a toxoid
    • coat protein that surrounds the pathogen called a capsule
    • other important proteins that are conserved by the pathogen
  • Select examples of vaccines against pathogenic bacteria include
    • DTaP that is composed of
      • C. diptheriae toxoid
      • C. tetani toxoid
      • B. pertussis toxoid
    • H. influenzae capsular type B
    • S. pneumoniae that comes in two forms including
      • a pediatric version with
        • 7 capsule types
        • think: a 7 year old gets PCV
      • an adult version with
        • 23 capsular types
    • N. meningitidis with 4 capsular proteins
  • Parenterally delivered vaccines are not effective against mucosal bacteria due to inferior secretory IgA response 
    • Examples of mucosal bacteria
      • E. coli
      • V. cholerae
    • Orally delivered vaccines are allow direct antigen contact with mucosa, generating a strong secretory IgA response 
 

References

 

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(M1.IM.13.78) A young man about to leave for his freshman year of college visits his physician in order to ensure that his immunizations are up-to-date. Because he is living in a college dormitory, his physician gives him a vaccine that prevents meningococcal disease. What type of vaccine did this patient likely receive? Tested Concept

QID: 100499
1

Live, attenuated

15%

(28/193)

2

Killed, inactivated

15%

(29/193)

3

Toxoid

3%

(5/193)

4

Conjugated polysaccharide

62%

(120/193)

5

Killed, attenuated

5%

(10/193)

M 1 D

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