Specific Immunity and Immunizations Flashcards Preview

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Flashcards in Specific Immunity and Immunizations Deck (12):
1

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

2

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)

3

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)

4

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

5

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

6

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

7

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)

8

Discuss the basic principles of vaccine policy.

Goals = to prevent disease in:
o Individual
o Population
o Earth (eradicate disease)

9

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

10

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.

11

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

12

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