Stratagiess of Vaccination

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					Strategies of Vaccination
      Behavioral Objectives
The student should be able to:
• Differentiate between active and passive
  immunization.
• Compare and contrast the advantages &
  disadvantages of immunizing with inactivated
  vs live vaccine agents.
• List at least 4 attributes of an ideal vaccine
  and elaborate on why they are important.
  Goal of Immunization is to
achieve a degree of immunity
sufficient to protect individuals
    from infectious disease
Aims of Disease Control to be
  Achieved by Immunization
• Containment-accepts that disease will remain
  endemic but seeks to reduce morbidity to an
  acceptable level.
• Elimination-no endemic transmission in a population.
  Sporadic cases will occur because of imported cases,
  but transmission in immunized population fails to re-
  establish endemic transmission. Need to establish
  herd immunity.
• Eradication- global destruction of pathogen allowing
  for cessation of all control measures achieving huge
  cost benefits for future generations. Requires the
  absence of an animal host and a vaccine effective in
  preventing disease transmission. Smallpox only
  human disease eradicated thus far.
       Immunity to Infectious
            Diseases
• Active immunity results from natural infection
  or by artificial means through vaccination.
  applied to susceptible populations of
  subjects. Long lasting in duration. Can be
  boosted.
• Passive immunity is also achieved by natural
  means during fetal life or through nursing. It is
  also gained by the transfer of antibody from
  one individual, human or animal, to another
  by injection. Usually applied to individual
  subjects. Short lasting in duration. Does not
  induce memory.
              Vaccination
• Active immunity produced by vaccine.
• Immunity and immunologic memory similar to
  natural infection but without risk of disease
  and of shortened duration.
• Vaccine-induced immunity to most infectious
  disease agents based on protective
  antibodies.
Classification of Vaccines
   • Live attenuated


   • Inactivated
 Examples of Live Attenuated
         Vaccines
• Viral         measles, mumps,
                rubella, varicella/zoster,
                yellow fever, rotavirus,
                intranasal influenza,
                rotavirus, vaccinia

• Bacterial BCG, oral typhoid
   Live Attenuated Vaccines
• Attenuated (weakened) form of the
  "wild" virus or bacterium
• Must replicate to be effective
• Immune response similar to natural
  infection
• Usually effective with one dose*

  *except those administered orally
      Disadvantages of Live
      Attenuated Vaccines
• Severe reactions possible
  in immunocompromized hosts.
• Reversion of vaccine strain can produce
  vaccine associated disease.
• Viral Interference
• Inclusion of contaminants (SV40 virus)
• Interference from circulating antibody
• Costly
• Fragile – must be stored and handled
  carefully
Inactivated Vaccines
Whole
 • viruses
 • bacteria

 • protein-based
   – toxoid
   – subunit

 • polysaccharide-based
   – pure
   – conjugate
        Inactivated Vaccines
• Cannot replicate
• Generally not as effective as live vaccines
• Less interference from circulating antibody
  than live vaccines
• Generally require 3-5 doses
• Immune response mostly humoral
• Antibody titer may diminish with time
  Examples of Inactivated
           Vaccines
Whole-cell vaccines
• Whole organisms
    Viral         polio, hepatitis A,
                          rabies, influenza*

     Bacterial            pertussis*, typhoid*
                          cholera*, plague*

  *not available in the United States
-Subunit   hepatitis B, influenza,
           acellular pertussis,
           human papillomavirus,
                 anthrax


-Toxoid    diphtheria, tetanus
   Polysaccharide Vaccines
Pure polysaccharide
     • pneumococcal
     • meningococcal
     • Salmonella Typhi (Vi)
     • Haemophilus influenzae type b
Conjugate polysaccharide
     Disadvantages of Pure
    Polysaccharide Vaccines
• Not consistently immunogenic in children
  younger than 2 years of age.
• Immunologic memory not induced
• Antibody isotypes with less functional activity
  produced
• Immunogenicity improved by conjugation to
  proteins/peptides (will hapten-carrier effect
  influence development of immunologic
  memory?)
Properties of an Ideal Vaccine
     According to WHO
•   Safe
•   Affordable worldwide
•   Heat stable
•   Effective after a single dose
•   Applicable to a number of diseases
•   Administered by a mucosal route
•   Suitable for administration early in life
            Vaccine Safety
•   Lubeck disaster
•   Cutter laboratory incident
•   MMR vaccine and autism
•   Rotavirus vaccine and intussusception
              Affordability
•   Vaccines are expensive to make
•   Big pharma needs incentives
•   Liability
•   International, National and Foundation
    support (Public and private sector
    support)
           Heat Stability
• Your primary care doc’s office vs an
  African village
• Need for a “cold chain”
    Effective in a Single Dose

• Should not be a problem in
  industrialized counties with adequate
  health care infrastructure.
• Necessary in developing countries
  where people may never be seen again.
   Applicable to a Number of
           Diseases

• BCG prevents tubercular meningitis and
  miliary tuberculosis in children
• BCG fail to elicit protective immunity to
  pulmonary tuberculosis in adults
   Vaccine Administration by
       Mucosal Routes
• Especially important in immunization
  programs involving large numbers of
  people.
   -cost effectiveness
   -logistical advantage
   -safety
   Immunization Early in Life
• Most vulnerable at this age
• Good compliance because of
  dependency for care.
• Stop transmission to older susceptible
  members of population
How to Get People Immunized
• Education, Education, Education
    -Public health educators
    -Health care providers and their
     organizations
    -Media
 Why Focus on Strategies to
  Increase Immunization?
• Immunization levels not optimal
• Cost-effectiveness of some strategies
  uncertain
• Sustainable systems needed
             AFIX
Assessment     AFIX is a quality
                 improvement
Feedback         strategy to raise
                 immunization
Incentives       coverage levels and
eXchange         improve standards of
                 practices at the
                 provider level.
            Assessment
• Evaluation of medical records to
  ascertain the immunization rate for a
  defined group
• Diagnosis of potential service delivery
  problems
• Assessment increases awareness
Special Characteristics of AFIX
• Focuses on outcomes
• Focuses on providers
• Blend of advanced technology and
  personal interaction
             Feedback
• Informing immunization providers about
  their performance
• Assessment with feedback creates the
  awareness necessary for behavior
  change
  How to Provide Feedback
• With feeling and precision
• Without judgment
• With confidentiality as appropriate
            Incentives
• Something that incites to action
• Vary by provider and stage of progress
• Opportunities for partnership and
  collaboration
   eXchange of Information
• Allows access to more experience than
  an individual can accumulate
• Motivates improvement
• Coordinates resources
  and efforts
               VFC/AFIX

• Incorporate AFIX activities during
  Vaccine for Children (VFC) site visits
• Combine VFC/AFIX site visits
• Reduces number of visits
• Extends reach of AFIX
CDC Vaccines and Immunization
              Contact Information



• Telephone      800.CDC.INFO

• Email          nipinfo@cdc.gov

• Website        www.cdc.gov/vaccines
Assignment: read chapter,”Vaccination
Strategies” in the Pink Book.

http://www.cdc.gov/vaccines/Pubs/pinkbook/default.h
tm

				
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posted:3/29/2011
language:English
pages:36