Vaccines provide immunity against disease by introducing an antigen to stimulate the immune system. There are two main types of immunization - passive which transfers antibodies, and active which relies on natural infection or vaccines. Vaccines work by activating the immune system's memory cells to recognize and fight pathogens. Different vaccine types include live attenuated or inactivated whole organisms, purified components, recombinant antigens, and more. Factors like incubation period and immune response determine which vaccine approach is best. Vaccines have had a major positive impact on public health by eradicating smallpox and reducing cases of diseases like measles.

1. VACCINE

2. VACCINE DEFINITIONVACCINE DEFINITION
 An antigenic substance prepared from the causative agent
of a disease or a synthetic substitute, used to provide
immunity against one or several diseases.

3. Types of Immunization
• Passive Immunization
 Methods of acquisition include natural maternal
antibodies, antitoxins, and immune globulins.
 Protection transferred from another person or animal.
• Active Immunization
 Methods of acquisition include natural infection,
vaccines (many types), and toxoids
 Relatively permanent.

4. • Concept of Immunity
• Self vs. Non-self
• Antigen specificity
• Indicated by presence of effector cells
• Protection from infectious diseases using above methods
Principles Underlying Vaccination

5. Vaccinations
Boosters (multiple inoculations) are required
Interference of passive maternal antibodies

6. Development of Vaccines
Common misconception that activation of the immune
system results in protective immunity
Multiple factors affect decisions when making
vaccines
1. Activation of specific branch of immune system
2. Development of immunological memory

7. Role of Memory Cells
 Depends on incubation period of pathogen
◦ Short Incubation Periods
 ex. Influenza
 Symptoms already under way by the time memory cells are
activated
 Repeated immunizations with neutralizing antibodies
◦ Long Incubation Periods
 ex. Poliovirus
 Enough time to allow memory B cells to respond

8. Types of VaccinesTypes of Vaccines
 Whole-Organism
◦ Attenuated Viral/Bacterial
◦ Inactivated Viral/Bacterial
 Purified Macromolecules
◦ Polysaccharide
◦ Toxoid
◦ Recombinant Antigen
◦ Recombinant-Vector
 DNA
 Synthetic Peptide
 Multivalent Subunit

9. Whole-Organism VaccinesWhole-Organism Vaccines
 Many common vaccines used consist
of inactivated or attenuated bacterial
cells or viral particles
 Includes attenuated and inactivated
vaccines

10. Attenuated Viral or Bacterial VaccinesAttenuated Viral or Bacterial Vaccines
 Attenuation – to reduce in force, value, amount, or degree;
weaken
◦ Achieved by growth under abnormal culture conditions
◦ Bacillus Calmette-Guerin (BCG)
◦ Act as a double edged sword, as they have distinct
advantages and disadvantages.

11. Advantages of Attenuated Bacterial or ViralAdvantages of Attenuated Bacterial or Viral
VaccinesVaccines
 Advantages stem from their capacity for transient growth
 Prolonged immune-system exposure
 Single immunizations
 Replication within host cells

12. Disadvantages of Attenuated Bacterial or ViralDisadvantages of Attenuated Bacterial or Viral
VaccinesVaccines
 MAJOR disadvantage is possible reversion
◦ ex: Rate of reversion of Sabin Polio vaccine is one case
in 4 million doses
 Presence of other viruses as contaminants
 Unforeseen post vaccine complications

13. Inactivated Viral or Bacterial VaccinesInactivated Viral or Bacterial Vaccines
 Methods of inactivation include heat or chemical agents
◦ End result…. Loss of replication ability
 Difficult to inactivate due to potential for denaturation of epitopes
◦ Dependence on higher order levels of protein structure

14. Attenuation vs. InactivationAttenuation vs. Inactivation

15. Attenuation vs. InactivationAttenuation vs. Inactivation
 Attenuation
◦ Normally require one dosage to induce relatively permanent
immunity
◦ Primarily cell-mediated in nature
◦ Despite reliance on cell-mediated immunity, increased IgA
response
 Inactivation
◦ Requires multiple boosters
◦ Emphasis on activating humoral immunity

16. AdjuvantsAdjuvants
 Adjuvants are CRITICAL for the use of inactivated vaccines
 Most widely used are aluminum salts (mainly hydroxide or
phosphate)
 Effects include liberation of antigen, chemo attraction, and
inflammation

17. Impact of Vaccines on Public HealthImpact of Vaccines on Public Health
 Between 1977 and 1980, smallpox was eradicated in the United
States
◦ Global eradication is currently a major consideration
◦ Phenomenon of herd immunity
 Measles occurrences at a record low

18. Thanks