Transcript Active Immunization

Core Tutorial
in Pediatric Infectious Diseases
for Third Year Medical Students
Immunizations
A fifteen-month-old child is seen for
“routine care”. He is due to receive his
MMR. On exam he has a temperature of
99 F and a runny nose.
Should he still be immunized? What are
the contraindications to immunization?
A twelve-month-old child has been taking
2 mg/kg/day of oral prednisone for the
past two weeks for asthma. He is due for
his routine immunizations.
Would you modify his immunization
schedule and if so, why?
Learning Objectives
• Understand the role of vaccine
components in the development of the
immune response
• Be able to differentiate active from
passive immunization and know the
indications for each
• Know the principles of vaccine safety
including side effects and
contraindications
PASSIVE vs. ACTIVE
Immunization
• Passive: Administration of preformed
antibody (immune globulin = IG) either
nonspecific or specific
• Active: Administration of antigen that
stimulates protective antibody
Indications for PASSIVE
Immunization
• Active immunization unavailable or
contraindicated
• Immunodeficient persons
• High likelihood of exposure
• No time for active immunity to develop
• When disease is present, to ameliorate or
aid in suppression of toxin effects or
inflammatory response
Non-specific Immune Globulin
• 2 types of nonspecific IG:
– Intramuscular
– Intravenous
• Both derived from pooled plasma of adults
• 95% IgG, with trace IgA, IgM
• Levels of antibodies in IVIG reflect those of
general population (and must have
minimum concentration of measles,
diphtheria, polio and hepatitis A)
Specific Immune Globulin
• Specific IG is available for:
–
–
–
–
–
–
Hepatitis B
Rabies
Tetanus
Varicella Zoster
Cytomegalovirus
Respiratory Syncytial Virus
Side Effects of
Immune Globulin
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•
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Pain, discomfort at injection site
Flushing, headache, chills, nausea
Chest pain, dyspnea, anaphylaxis
Development of antibodies against
heterologous IgG
• Development of anti-IgA antibodies in
patients with IgA deficiency
• Need to delay active immunization
ACTIVE Immunization
• Administering all or part of
microorganism or modified product (e.g.
toxoid, purified antigen or antigen
produced by genetic engineering) to
evoke immunologic response mimicking
that of natural infection.
• Protection is measured indirectly as
antibody titers
Vaccine Constituents
• Intact infectious agent (all or part of organism):
can be live-attenuated or killed (inactivated)
• Toxoids (modified product of organism): These
are bacterial toxins that are modified to make
them non-toxic. They induce formation of
antibodies against toxin to protect against toxinmediated illness (e.g. tetanus, diphtheria).
Other Vaccine Constituents
• Suspending Fluid - sterile water or saline,
possibly with proteins or other
components e.g. egg antigens, gelatin
• Preservatives, Stabilizers, Antibiotics Mercurials, such as thimerosal, and
antibiotics, such as neomycin and
streptomycin, are often added to prevent
bacterial growth or stabilize the antigen.
May be implicated in allergic reactions.
Other Constituents, con’t.
• Adjuvants - Substances (e.g. aluminum
salt) added to increase immunogenicity
and prolong the stimulatory effect,
especially for inactivated microorganisms
or their modified products
Routes of Administration
• There is no single preferred site for all
injectable vaccines
• Most vaccines are given by the
intramuscular or subcutaneous routes
• Other routes include intradermal and
nasal
• Will depend on active constituents
Routes of Administration,
con’t.
• Intramuscular: DTaP, Influenza, Hepatitis
B, Hib, Pneumococcal conjugate
• Subcutaneous: MMR, IPV, Varicella
• Intradermal: BCG
• Nasal: influenza (under investigation)
Vaccine
Schedules
• Based on age-specific attack rates of
disease, disease risks, and age-specific
immune responses
• Based on vaccine product type
• Based on trials which determine immune
titer after vaccine is administered
Schedule of Required
Childhood Vaccines
Depends on type of vaccine, immunity that
develops, duration of immunity, age at initial
immunization, level of exposure to disease
– 5 DTaP (diphtheria, tetanus and acellular
pertussis)
– 4 Hib (Haemophilis influenzae type B) and IPV
(inactivated poliovirus)
– 3 Hepatitis B
– 2 MMR
– 1 VZV (varicella zoster virus)
Current Schedule
www.aap.org/family/parents/immunize.htm
Other Vaccines
(recommended for certain groups)
• Influenza vaccine
– chronic illness, ?all children
• Hepatitis A vaccine
– certain areas of U.S., travelers
• Meningococcal vaccine
– travelers, ?college students
• Typhoid
– travelers
Common Side Effects
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•
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Usually mild to moderate and self-limited
Local inflammation at the site of injection
Fever, irritability, lethargy
Sterile abscesses usually occur after
killed vaccines due to irritation by
vaccine or adjuvant, or because of
inadvertent injection of an intramuscular
vaccine subcutaneously
Rare Side Effects
• Tend to have permanent sequelae or even
be life-threatening
– Paralytic polio after administration of OPV
vaccine.
• Severe hypersensitivity reactions such as
anaphylaxis; often due to vaccine
components such as egg antigens,
thimerosal, neomycin, or infectious agent
MMR Vaccine & Autism
• 1998, Great Britain: 12 children with developmental
disorders and gastrointestinal disturbances
• ?link between MMR vaccine and subtype of autism
that includes bowel symptoms
• 2001, Institute of Medicine: concluded that there
was no evidence that the MMR vaccine leads to
autism
• 2001, British Public Health Laboratory Service:
“No epidemiology could prove that a vaccine never
causes autism…proof of a negative is impossible”
Contraindications
• Hypersensitivity to the (previously
administered) vaccine or its components
• Immunocompromised state or pregnancy
(for live vaccines)
• Undefined illness, moderate to severe
febrile illness, or progressive neurological
conditions until stabilized
Contraindications for
Specific Vaccines
• DTaP/DTP: encephalopathy within 7
days of previous DTaP or DTP
• MMR: pregnancy, immunodeficiency,
long-term immunosuppressive therapy,
severe HIV disease
• Varicella: pregnancy, immunodeficiency,
long-term immunosuppressive therapy,
HIV
• Hepatitis B: anaphylactic reaction to
baker’s yeast
Not Contraindications
• Current or recent mild illness with or
without a low grade fever.
• Current or recent antibiotic therapy.
• Previous mild to moderate local
tenderness, redness, swelling.
• Fever <40.5 C after any vaccine.
• Family history of seizure disorder.
• Breastfeeding.
Impact of Vaccination Programs
Smallpox
Annual Morbidity Annual Morbidity
Before Vaccine
After (1995)*
48,164 (1900-1904)
0
Poliomyelitis
(paralytic)
Diphtheria
16,316 (1951-1954)
1
175,885 (1920-1922)
1
Measles
503,282 (1958-1962)
100
* These figures represent 100% reduction in morbidity
th
(rounded to the nearest tenth). Source: Red Book 2000, 25
Edition, American Academy of Pediatrics, p. 2.
References
• Active and Passive Immunization. Red
Book 2000, 25th ed. American Academy
of Pediatrics, 2000; Chapter 1.
• Marchant CD, Kumar ML.
Immunizations. In: Pediatric Infectious
Diseases, Principles and Practice. HB
Jensen and RS Baltimore, eds. 1995;
pp295-326.
Questions for Discussion
1 of 5
A fifteen-month-old child is seen for
“routine care”. He is due to receive his
MMR. On exam he has a temperature of
99 F and a runny nose.
Should he still be immunized? What are
the contraindications to immunization?
Questions, con’t
2 of 5
A twelve-month-old child has been taking
2 mg/kg/day of oral prednisone for the
past two weeks for asthma. He is due for
his routine immunizations.
Would you modify his immunization
schedule and if so, why?
Questions, con’t
3 of 5
A two-month-old girl is brought to the
office for a well child examination. The
mother is concerned about the potential
complications of immunizing her child.
How would you address this issue with
the mother?
Questions, con’t
4 of 5
A four-month-old boy is seen for a well
child examination. Following his first set of
immunizations he had a temperature of 103
for a day and extreme irritability. The
parents are concerned about giving the
second set of immunizations.
How would you address their concerns?
Can he be immunized today?
Questions, con’t
5 of 5
The parents of a two-month-old girl want
to know why their child has to be
immunized. None of their friends, family
members, or neighbors has ever had
hepatitis B virus infection, tetanus,
diphtheria, or polio.
What would be your response?