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 NaturalAttenuated Killed vaccines Note: Living organisms tend to be more effective as vaccines

Natural live vaccines are rarely used !! Attenuated live vaccines are highly SuccessfulAttenuation 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 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 DisadvantagesAdvantages Slower onset of immunityMore stable in storage Likely to cause allergic reactions Available for a wide variety of diseases More expensive than live- attenuated vaccines No risk of reverting to virulent form May not produce as strong or as long lasting immunity as the live-attenuated products Excellent stimulant of passive Abs in colostrum

Basic Vaccination Schedule in The Kingdom of Saudi Arabia