VACCINATION
Vaccination:
Is The administration of an antigen to
stimulate a protective immune
response against an infectious agent
Aims & Objectives of
Immunization
 Prevention
of serious diseases and their
complications
 Protection of individuals and communities
 Containment of outbreaks
 Elimination of certain diseases, e.g. tetanus
 Eradication of diseases,
e.g. smallpox (1980) & polio (target date 2006)
EXAMPLES OF VACCINES:
 Killed
or Attenuated organisms
vaccines
 Microbial Fragments Vaccines
 Modified Toxins to Toxoid vaccines
 Anti- idiotype antibodies & DNA
vaccines
Requirements for A vaccine:
1- Safe to administer
2- Induce the right sort of adaptive immunity
3- Affordable
USE OF ANTIGENTS AS VACCINES:
Live vaccines
Natural
Attenuated
Killed vaccines
Note: Living organisms tend to be more
effective as vaccines
Natural live vaccines are rarely used !!
Attenuated live vaccines are highly
Successful
Attenuation
Changing microorganisms to make them
less able to grow and diseases in their
natural host
Easier to attenuate viruses than bacteria
 Inactivation
of toxins is the most effective
and successful bacterial toxins
 Tetanus
and diphtheria vaccines are
based on this method
 Same
approach can be used for many
other bacterial infections.
FUTURE VACCINES:
Use recombinant DNA and gene cloning:
 Insert
desired gene into a vector
 Inject vector to patient
 Allow to replicate
 This will produce large amount of Ag in
situe
Factors that affect vaccine effectiveness:
1- Induction of the right sort of immunity
2- Be stable on storage
3- Have sufficient immunogenicity
Q: What is an adjuvant?
4- Safety
5- Cost
Live –Attenuated Vaccines:
Advantages One initial dose is usually sufficient but
additional boosters doses may be required
 Causes less allergic reactions than KV
products
 More rapid protection than KV products
 Tend to be less expensive
Disadvantages
 Must be handled and mixed with additional
care
 Potential for excessive immune response
 Some risk of causing abortion or transient
infertility
 Potential to mutate to a virulent form
Killed vaccines (KV) and Toxoids
Advantages
Disadvantages
More stable in storage
Slower onset of immunity
Available for a wide variety of
diseases
Likely to cause allergic
reactions
No risk of reverting to virulent
form
More expensive than liveattenuated vaccines
Excellent stimulant of passive
Abs in colostrum
May not produce as strong or as
long lasting immunity as the
live-attenuated products
Basic Vaccination Schedule in The
Kingdom of Saudi Arabia