Specific Immunity and Immunizations Flashcards
Describe the principles of active immunization
Application of an antigen to induce an immune response that is protective and induces immunologic memory
Important:
• Producing Ab’s is NOT enough = Ab must be able to neutralize infection
• Memory cells = allow for more rapid immune response
• Booster doses generate more memory cells and Ab producing cells → sustained protection
Describe the principles of passive immunization
Transfer of immunity from one individual to another
Types: 1) Natural = Mother to child • Maternal IgG transferred across placenta to fetus in utero o Protect for first 6 months • Breast mild contains IgA Ab = transferred to nursing infant 2) Drug = purified Ab (IgG) • Immunoglobulin • Gamma globulin • IV immune globulin (IVIG)
Medical uses:
• Treatment of immune deficiency (Ex: congenital agammaglobulinemia)
• Pre-exposure (Ex: travelers to prevent Hep A)
• Post-exposures (Ex: rabies immune globulin after bat bites)
Sources of immunoglobulin
• Horse immunoglobulin (ex: snake bite infection)
• Pooled human plasma = contains all the Ab’s present in donors (Ex: Hepatitis A immune globulin)
• Specific high titer human immunoglobulin from immunized donors (Ex: Varicella Immune globulin)
• Monoclonal Ab produced in vitro (Ex: RSV antibody)
Avantages vs. Disadvantages of Active (both attenuated and inactivated vaccines) and Passive immunity
Active immunity: Attenuated Vaccines
Adavantages:
-Provide prolonged immune system exposure → excellent immune response (both humoral and cellular)
-May not need or may need less boosters
Disadvantages:
-Produces minor or sub-clinical case of disease
-Rarely = potential to revert back to virulent form → full blown disease
Ex: measles, varicella, oral polio
-Recipient may “shed” vaccine strain of organism → inadvertent transmission to contacts (potential for both harm and good)
-Potential risk in pregnant women = cause disease in infant
Active immunity: Inactivated Vaccines
Advantages:
-Cannot reproduce in host
Disadvantages:
-Require boosters (since only produce humoral response)
-Whole organism vaccines = more potential for adverse effects than purified subunit vaccine
Passive immunity Advantages: -Rapid onset of action (hours) -Not dependent on functional immune system -Very effective Disadvantages: -Expense -Adverse events (esp anaphylaxis) -Short duration of action (weeks to months) -Parenteral administration (IV or IM)
List the possible components used in vaccines
1) Types of antigens:
- Attenuated organisms (“live”)
- Inactivated organisms (“killed”)
- Purified subunits: toxoid vaccines, polysaccharide vaccines, conjugate vaccines, surface antigen vaccines
2) Other components:
- Adjuvant
- Preservatives
- Antibiotics
- Vector remains
Differentiated between attenuated and inactivated antigens in vaccines
Attenuated organisms (“live”) • Weakened microorganisms • Retain capacity to reproduce in host • Often = non-virulent mutants • Provide prolonged immune system exposure → excellent immune response (both humoral and cellular) • May not need or may need less boosters • Ex: oral polio
Inactivated organisms (“killed”)
• Whole pathogen killed by heat or chemical means
o Complex mixture of antigens → more potential for adverse effects
• Cannot reproduce in host
• Elicits mainly a humoral response
• Requires boosters
• Ex: inactivated polio virus, whole cell pertussis vaccine, some influenza
Describe the types of purified subunits used in vaccines
- Contain 1 or more purified molecules from organism
- Lower adverse effects rates than inactivated vaccines
Includes:
Toxoid vaccines
• Inactivated bacterial exotoxin
• Induces Ab to toxin → binds toxin → neutralizes
• May NOT prevent infection, but prevents disease manifestations
• Ex: tetanus, diphtheria vaccines
Polysaccharide vaccines
• Ab binds to polysaccharide capsule → phagocytosis → neutralization of organism
• Ex: pneumococcal vaccine, meningococcal vaccine
• Problem: children <2 years cannot develop Ab response to polysaccharide antigens YET most of mortality is in young children
Conjugate vaccines = covalently link polysaccharide capsule to protein
• Allows infant to develop immune response
• Ex: pneumococcal conjugate, Haemophilus influenza type B, meningococcal vaccines
Surface antigen vaccines
• Purified molecules on surface of organism
• Ex: Hepatitis B surface antigen, some pertussis vaccine components
Describe the use/purpose of adjuvant, preservatives, antibiotics, and vector remains in vaccines
Adjuvant
• Inert substance that results in increased Ab response to vaccine
• Binds to antigen → increased uptake by APC’s; increased cytokine synthesis
• Ex: alum (aluminum hydroxide)
Preservatives
• Thimerosol (mercury)
• Rarely used anymore
Antibiotics (neomycin) = preservatives
Vector remains (yeast or egg)
Discuss the basic principles of vaccine policy.
Goals = to prevent disease in:
o Individual
o Population
o Earth (eradicate disease)
Vaccine immunogenicity
o The ability of a vaccine to produce a measurable immune response in a population.
o Usually measured as a concentration of antibody in serum.
BUT not entire story:
• Inactivated polio vaccine → Ab production in 95% of recipients after 2 doses
• But not necessarily mean it prevents disease
Vaccine efficacy
o The ability of a vaccine to actually prevent disease in a population.
o Ex: efficacy of pertussis vaccine is 85% in children in Italy.
Herd Immunity
o Protection of a susceptible person by highly immunized population
o If high enough percentage of population is immunized → incidence of disease in population drops
Explain the factors that result in under-immunization and what can be done to improve immunization rates.
Parental apathy, lack of knowledge or forgetfulness
Doctor ignorance
o Ex: not understanding that a having a common cold does not contraindicate a vaccine.
Parental concern o About adverse events o Real or unproved o Misinformation o Ex: MMR and Autism = no link
Missed opportunity
o Not giving vaccines at every chance
o Ex: giving varicella vaccine when patient comes in for wart removal
Cost = vaccines are expensive
o Federal Vaccine’s For Children (VFC) program pays
o No child in the united states should be denied vaccine because of inability to pay
Number of Injections
o Current max 4-5 per visit
o Parental hesitation
o Provider hesitation
Cultural beliefs/ Religious beliefs
Logistical
o Transportation, work, school, wait times
Vaccine Shortages o Quality control / regulatory issues o Production problems o Financial decisions o Unanticipated demand
Record Keeping
o Records often incomplete
o Multiple providers
o Solution = computerized databases (Ex: Wisconsin Immunization Registry)
Fear of Lawsuits
o Vaccine Injury Compensation Fund
• Doctor or manufacturer cannot be sued
• Provides damages to patients injured by vaccine
Access to Care o No insurance o No medical home o Geography- far from clinic o Language/cultural barriers o Citizenship status
