1. Vaccines

2. History of vaccines Variolation to Vaccination Variolation Vaccination
Innoculation of smallpox into skin
Vaccination
Edward Jenner developed the modern practice of vaccination when he inoculated people with cowpox virus to protect them against smallpox.

3. How do vaccines work?
“Trick” human immune system into producing antibodies or immune cells
Induce protection against real disease-causing microbes
Do not cause illness but cause production of T cells and Antibodies
imitation infection can cause minor symptoms, such as fever. Such minor symptoms are normal and should be expected as the body builds immunity

4. What do we want to achieve with vaccines?
Herd Immunity
Large proportion of group is resistant  whole group is resistant
Results from effective vaccination programs (90% vaccinated  no spread of disease)

5. Immunologic Memory

6. Killed Inactivated vaccines
Also fight viruses
No danger of infection
Made by inactivating or killing the virus during the process of making the vaccine
Killed by treatment with heat or chemicals
Does not stimulate cell mediated immunity
Usually need booster vaccines
Examples
Salk Polio Vaccine and Rabies Vaccine

7. Toxoid Vaccines
Prevent diseases caused by bacteria that produce toxins (poisons) in the body
Some bacteria cause disease by producing toxins that invade the bloodstream
Toxins are weakened so they can’t cause illness
Toxoids
The immune system will learn how to fight off the natural toxin after receiving the vaccine with a toxoid
Examples
Diphtheria
Tetanus and Pertussis (DTaP vaccine- contains diphtheria and tetanus toxoids)

8. Subunit Vaccines Only use part of a bacteria or virus
Produce effective immune response without causing separate & potentially harmful immune reactions to the many antigens carried on microbe
Examples
DTaP vaccine (The pertussis component is an example of a subunit vaccine)
Typhoid
Hepatitis B

9. NOn-Infectious Vaccines
The first three vaccines named in these notes are considered to be non-infectious
Will make B-memory cells and T-helper memory cells
= good antibody response
-Will not make memory killer T cells
-Booster vaccines usually needed

10. Live attenuated VAccines
Fight viruses
Closest to natural infection
Contain a version of the living virus that has been weakened so that it does not cause serious disease in people with healthy immune systems
Not everyone can receive them
Children with weakened immune systems (ex: patients undergoing chemotherapy)
Examples
Sabin Polio Vaccine (not currently recommended)
Measles, Mumps, and Rubella Vaccine (MMR)
Varicella (chickenpox) Vaccine

11. Live Attenuated Vaccines
Makes memory cells: B-cells, T helper and Killer T cells
- Usually life-long immunity
Some viral shedding:
can produce disease in immunocompromised host

12. Conjugate Vaccines Fight different type of bacteria
Bacteria have antigens (Ag) with an outer coating of sugar-like substances called polysaccharides
Coating disguises the Ag
Coat isn’t recognized by immature immune systems of young infants therefore there is no response to it
These vaccines link together proteins or inactivated toxins from a 2nd organism to bacteria’s outer coat
Enables baby's immune system to respond to combined vaccine & produce antibodies
Causes immune response against disease-causing bacteria
Examples
Haemophilus influenzae type B (Hib vaccine)
Hib Previously major cause of bacterial meningitis in babies & young children

13. Safety of Vaccines Benefits of vaccines far outweigh their risks
The American Academy of Pediatrics, the Centers for Disease Control and Prevention, and the Institute of Medicine all conclude that the benefits of vaccines outweigh their risks
Thimerosal is a preservative that was found in most vaccines in the past. But now:
Only one third of flu shots still have thimerosal
NO other vaccines commonly used for children or adults contain thimerosal
Research done over many years has NOT shown any link between thimerosal and autism, or other medical problems
Source:

14. Source: CHAPTER 22 VACCINATION