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Basic immunology
and
practical aspects of immunization
2. Basic definitions
Immunity-process of fighting with infection, disease
and other unwanted biological invasions with having
adequate tolerance to avoid allergy and autoimmune
diseases.
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3. Are vaccination and immunization same?
Both used interchangeably but minor technical
difference
Vaccination – inoculation of antigen or vaccine into
the body. The recipient may or may not seroconvert
the vaccine
Immunization- actual process of inducing immune
response which can be humoral or cell mediated in
the recipient
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5. Innate Adaptive
Comprise of skin and
mucosal barriers,
phagocytes(neutro,mono
cytes and macrophages)
Response is antigen
independent
There is immediate
response
Exposure does not result
in induction of memory
cells
Comprise of humoral
and cellular immunity
There is a lag time
between exposure and
maximal response
It is antigen specific
Exposure result in
induction of memory
cells
Inmate and Adaptive immunity
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7. Humoral Cell mediated
Principal defence against
extracellular microbes.
Involves b lymphocytes
which produces antibodies
Antibodies act by
neutralisation, complement
activation, promoting
opsonophagocytosis
Antibodies are of different
types IgA, IgG,IgE,IgM,IgD
Principal defense against
intracellular microbes
Effectors are t cells that
May be helper or cytotoxic
Helper t cells secrete
cytokines that stimulate the
proliferation and
differentiation of t cells as
well as b cells and NK cells
The cytotoxic t cells acts by
lysing infected cells
Humoral vs cell mediated immunity
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8. What is a vaccine?
An immuno biologocal substance that is introduced
in the body to produce specific protection against a
given disease.
Antigenic but not pathogenic.
It often made from weakened or killed forms of the
microbe, its toxins or one of its surface proteins
The vaccine stimulates the body immune system to
recogonize the agent as a threat, destroy it and keep
a record of it so that the immune system can more
easily recogonise and destroy any of these micro-
organisms that it later encounters
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11. priming
By priming the immune system by vaccination,,
when the vaccinated individual is later exposed to
the live pathogen in the environment the immune
system can destroy them before they can cause
disease
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12. How do vaccine work?
Mainly by production of antigen specific antibodies
CMI just have supporting role in antibody
production
T cell independent mech in polysaccharide vaccines
Not stimulate CMI -no long lasting immunity
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13. Response after immunization
Vaccines attract dendritic and monocytic cells.
These migrate to LN and cause activation of T & B
lymphocytes
Killed
Local unilateral
LN activation
Live
Multifocal LN
activation due to
microbial
replication and
dissemination
Hence
immunogenecity
of killed less
than live{so
adjuvant
required}
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14. polysaccharide protein
T cell independent
Injection site to spleen
and directly bind with b
receptors
Response sets in 2to 4
weeks
Predomnantly with IgM
Immune response
T cell dependent
Trigger T cell which
stimulate b cell
causing germinal
center reaction
Plasma cell move to
bone marrow and
survive there resulting
in memory cells
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15. Determinants of intensity and duration of
immune responses
Depends on-
vaccine type, nature and vaccination schedule
Live attenuated more than inactivated
Nature- protein more than polysacharide
Vaccination schedule 0-1-6 schedule better than 6-
10-14.
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16. Type of vaccines
Live atteneuted vaccine- live bacteria rendered
avirulent
Inactivated vaccine-microorganisms killed by heat
and chemicals
Subunit vaccine- only the antigens that best
stimulate the immune system are included
Toxoid vaccine– modified exotoxins in which toxicity
lost but antigenecity remains
Conjugate vaccine
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17. Live attenuated
These are modified strains of pathogens that retain
anigenicity but lost its pathogenicity
May be bacterial or viral
These replicate or multiply in the body after
administration and stimulate the immune system
Eg viral- polio(sabin), measles,rubella, varicella,
yellow fever, rota virus
Bacterial-bcg and oral typhoid
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19. Killed
Organisms are killed by phenol, formaldehyde, and
gamma radiation
Usually safe but less effective than live vaccines
The only absolute contra indication is severe local or
general reaction to the previous dose
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20. toxoid
Detoxified toxins called toxoid is inactivated by
treating them with formalin a solution of
formaldehyde and sterlised water
These are used when bacterial toxins are main cause
of infection
Eg tetanus, diptheria
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22. subunit
include only the antigens that best stimulate the
immune system
use epitopes—the very specific parts of the antigen
that antibodies or T cells recognize and bind to.
Because subunit vaccines contain only the essential
antigens and not all the other molecules that make
up the microbe, the chances of adverse reactions to
the vaccine are lower.
Eg tetanus pertusis hep b
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24. types ADVANTAGES DISADVANTAGES
Live attenuated •Excellent immune
response
•sufficient time for
memory cell production
Revert to original form
can cause disease
Not given in
immunocompromised
Less stable
killed Safe
Cheap
Easy to store
Booster doses required
Only humoral response
there
Vaccine induced
disease can occur
Sub unit Have no live
component so no risk of
inducing the disease
Safe and stable
No guarantee of future
memmory cells
Low immune response
conjugated Exellent immune
response
No booster required
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25. Vaccine Efficacy
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It is percentage reduction in disease incidence
attributable to vaccination
Calculated by– VE=1-RV/RU*100
RU=attack rate in unvaccinated people
RV=attack rate in vaccinated indivisuals
Measles -90-95%, mumps-72-88%, rubella-95-98%
26. Vaccine Effectiveness
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Reduction in the clinical events that might be
expected to be associated with the disease but could
also to be caused by other agents.
Assesed by case control study and odds ratio
Effectiveness=(1-OR)*100
Basically it is attack rate among vaccinated vs attack
rate among non vaccinated
27. Vaccine Failure
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When fully vaccinated person develop the disease
against which they have been vaccinated its called
vaccine failure
Two types primary and secondary
Primary-when recipient does not produce enough
antibodies when first vaccinated
Secondary- adequate number of antibodies are
produced immediately after vaccination but level fall
over time
28. Concept of HERD immunity?
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Resistance of a group or a community
against invasion and spread of infectious
agents as a large number of grps being
immunized
May be in immunised or non immunised
individuals
Asessed by cross sectional and
serological surveys
29. Herd Effect
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It is reduction of infection or disease in the
unimmunized segment as a result of immunizing a
proportion of the population
OR
It is the change induced in epidemiology(incidence
reduction) among unvaccinated members when a
good proportion is vaccinated.
30. EPIDEMIOLOGICAL SHIFT
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Imp concept
Denotes change in pattern of disease in specified
population
Associated with partial immunization coverage
Disease of imp are hep A, rubella and varicella
Severity of disease worsens with advancing age
31. R O U T E S A N D T E C H N I Q U E S
G E N E R A L I N S T R U C T I O N S
F A Q S
Practical aspects of
immunisation
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32. Routes
With the exception of BCG and sometimes rabies, all
parentral vaccines are given by either intramuscular (IM)
or subcutaneous (SC) route.
The SC route is recommended for measles, MMR,
varicella, meningococcal polysaccharide, JE, Yellow fever
vaccines; either SC or IM route may be used for
pneumococcal polysaccharide vaccines, IPV; the rest of
the vaccines should be given intramuscularly.
there is no harm done if SC vaccines are given IM.
However, vaccines designated to be given IM should not
be given SC due to risk of side effects (as seen with
aluminium adjuvanted vaccines) or reduced efficacy (due
to reduced blood supply in SC tissue and hence reduced
immunogenicity).
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33. continued..
The gluteal region should never be used for
administration of IM injections due to risk of sciatic
nerve injury and reduced efficacy (rabies and hepatitis B
vaccines).
When used at the recommended sites where no large
blood vessels exist, pulling back of the syringe to check
for blood is not recommended.
The needle should be withdrawn a few seconds after
finishing administration of the vaccine (to prevent
backflow of vaccine into the needle track) following
which the injection site should be pressed firmly for a few
seconds with dry cotton. The injection site should not be
rubbed following injection
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35. General instructions
Vaccination at birth means as early as possible within 24 to 72
hours after birth or at least not later than one week after birth.
Whenever multiple vaccinations are to be given simultaneously,
they should be given within 24 hours if simultaneous
administration is not feasible due to some reasons.
The recommended age in weeks/months/years mean completed
weeks/months/years.
Any dose not administered at the recommended age should be
administered at a subsequent visit, when indicated and feasible.
The use of a combination vaccine generally is preferred over
separate injections of its equivalent component vaccines.
When two or more live parenteral/intranasal vaccines are not
administered on the same day, they should be given at least 28 days
(4 weeks) apart; this rule does not apply to live oral vaccines.
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36. If given<4 weeks apart, the vaccine given 2nd should
be repeated
The minimum interval between 2 doses inactivated
vaccines is ussually 4 weeks
Vaccines doses administered upto 4 days before the
minimum interval or age can be counted as valid. If
the vaccine is administered >5days before minimum
period, it is counted as invalid dose.
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37. Changing needles between drawing vaccine into the syringe and
injecting it into the child is not necessary.
Different vaccines should not be mixed in the same syringe unless
specifically licensed and labeled for such use.
Patients should be observed for an allergic reaction for 15 to 20
minutes after receiving immunization(s).
When necessary, 2 vaccines can be given in the same limb at a single
visit. The anterolateral aspect of the thigh is the preferred site for 2
simultaneous IM injections because of its greater muscle mass.
The distance separating the 2 injections is arbitrary but should be at
least 1 inch so that local reactions are unlikely to overlap
A previous immunization with a dose that was less than the
standard dose or one administered by a nonstandard route should
not be counted, and the person should be reimmunized as
appropriate for age.
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39. Question 1
Am too scared about side effects of vaccines
after media reports.
Answer
Serious side effects are extremely rare
and mostly due to human error, rather
than vaccine itself
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40. QUESTION 2
My child was immunised against this disease, yet
he/she got it. Why?
No vaccine provides 100 percent protection.
the incidence is decreased drastically, and even if
the child gets the disease, it is mild.
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Question 3
•My child has so many pending vaccinations.
Can they be given 1 week apart, so as to
finish them early?
•No.
•Any number of vaccines can be given on the
same day.
however, if not given on the same day, a
minimum of 28 interval should be maintained
before next vaccination.
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Question 4
I have missed giving my child a vaccine at the
recommeded date. Should I start all over again
No. immune system has good memory function.
No need to restart schedule. Continue from
where u left.
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QUESTION 6
Shud I give the optionalk vaccines? Especially the expensive
ones?
All optional vaccines should be given if affordable
They are effective