VACCINES
https://www.youtube.com/watch?v=rb7TVW77ZCs
HISTORY OF
VACCINES
• Variolation to Vaccination
• Variolation
•
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.
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
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)
IMMUNOLOGIC MEMORY
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
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)
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
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
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
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
CONJUGATE VACCINES
•
Fight different type of bacteria
•
Bacteria have antigens (Ag) with an outer coating of sugar-like
substances called polysaccharides
•
•
These vaccines link together proteins or inactivated toxins from a 2nd
organism to bacteria’s outer coat
•
•
•
Coating disguises the Ag
•
Coat isn’t recognized by immature immune systems of young infants
therefore there is no response to it
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)
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: http://www.nlm.nih.gov/medlineplus/ency/article/002024.htm
Source: CHAPTER 22 VACCINATION