Specific defences :
Micro organism-breach local defense systems
host recognize, destroy and eliminate antigenic
material foreign to its own
Specific defenses are
1.Active immunity – humoral, cellular , combined
immunity
2.Passive immunity – normal human Ig, specific human
Ig, animal antitoxin or antisera
 Active immunity
- Immunity developed as a result of infection or by
specific immunization and is usually associated with
the presence of Ab or cells having specific action on
micro organism or its toxin. - Immunity produced is
specific for particular diseases
Active immunity may be acquired by following :
-clinical infection
-sub clinical or in apparent infection
-immunization with an antigen
THE IMMUNE RESPONSE
A. Primary response:
-Ag first time administer IgMAb -----IgGAb
-Nature and extend of primary response to an
Ag is determined by factors like
-Dose of Ag, nature of Ag, route of
administration, nutritional status of the host etc.
 Following primary response RES is educated . There s
production of memory cells by both B & T
lymphocytes
 These cells are responsible for immunological memory
which become established after immunization
 In fact purpose of immunization is to develop
immunological memory.
B. Secondary (booster) response:
-secondary response involve production of both IgM &
IgG antibody
Response to booster dose differs in a no. of ways from
primary response
(a) Production of Ab more rapid
(b) Ab response maintained at higher level for a long
period of time
(c) Ab tends to have a greater capacity to bind to Ag
Humoral immunity
 It comes from B cells (bone marrow derived
lymphocytes) which proliferate and manufacture
specific Ab after Ag presentation by macro phages
 Immunoglobulin's are divided into 5 classes – IgG,
M,A,D &E .
 they circulate in body and neutralizes the
microbes/toxins
 Ab are specific- they react with same Ag when
provided
Cellular immunity
 Some micro organism like M.Leprae , M.TB escape
humoral immunity and can multiply in macrophages .
However these macrophages can be stimulated by Tlymphocytes.
 The activated macrophages perform a much more
efficient phagocytic function than non- activated
macrophages
 T cells do not secrete Ab , but they are responsible for
recognition of Ag
Combination of both
 In some cases they jointly helps in immunity
 Vaccine to be effective must ellicit both cell mediated
and humoral responses
 Active immunity takes time to develop . It is superior
to passive immunity because
(a) duration of protection is long lasting
(b) With few exceptions severe reactions are rare
(c) Protective efficiency is better than passive
(d) Active is less expensive
Passive immunity
 Ab produced in one body ( human / animal ) are
transferred to another to induce protection against
disease
 That is, they are ready made Ab
 Passive immunity may be induced by
(a) Ig or anti serum administration
(b) Ab through placenta , human milk (IgA)
 Passive immunity differ from active immunity by
(a) Immunity is rapidly established
(b) Immunity produced is only temporary ( days to
months ), till when Ab is eliminated from the body
(c) There is no education of RES
Herd immunity
 It is the level of resistance of a community or a group
of people to a particular disease
 Eg: polio vaccine-------, chickgunya in Alappuzha
 Elements contributing to herd immunity
(a) Occurrence of clinical or sub-clinical infection in
herd
(b) Immunisation of the herd
(c) Herd structure
 If herd immunity high enough , occurrence of
epidemic is highly unlikely
 Herd immunity is maintained by immunisation
 Eg: polio , diphtheria
 With no vaccine for small pox herd immunity is
declined
Immunising agents
 Vaccines- substances-designed to produce specific protection
against a given disease
 It stimulate production of protective Ab
(a) Live vaccine (attenuated )
Prepared from live organisum . Doesn’t have the property of
phathogenicity but retained immunogenicity
Should not be administered to immune deficient people,
pregnancy
If two live vaccine required – either given at two sites
simultaneously or with an interval of at least three weeks
Should be properly stored
Usually require only one dose , exception of polio
Eg: polio , BCG , measles , rubella
(b) Inactivated / killed vaccine
Virus is killed with heat or chemicals and infected into the
body to stimulate active immunity
They are usually safe but less efficacious than live vaccines
Usually require more than two to three primary and even a
booster dose to produce adequate Ab response
Usually administered i/m or s/c
Only severe C/I is severe local or general reaction to previous
dose
Eg: pertusis , IPV, typhoid
 Toxoid:
Exotoxins produced by certain organisum are
detoxicated and used to prepare vaccines
These Ab produced neutralises the toxin moiety
produced during infection and not the organism
Highly efficacious and safe
Eg : tetanus and diphtheria
 Cellular fraction:
Prepared from extracted cellular fractions like cell wall,
capsule etc
Efficacy and safety high
Eg : meningiococcal, pneumococcal
 Combination:
Simplify administration, reduce cost, minimise no. of
contact of patient with health system
Eg : DPT , MMR, Pentavalent
 Polyvalent : prepared from two or more strains of same
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species . Eg : polio infuenza
Autogenous vaccine : organism in vaccine is obtained
from the same patient
Vaccine can be plain , adjuvant , freeze dried
preparation
Adjuvant is added to vaccine with an intent of
potentiating the immune response.eg : aluminium
phosphate, aluminium hydroxide
Freeze dried vaccines ( BCG , Measles , YF) are more
stable preparations than liquid vaccines
Immunoglobulin
 Composed of five major classes and its sub units-
IgG,M,D,A,E
 Ig preparations : two types
(a) Normal human Ig
(b) Specific human Ig – usually made from plasma of
patients who have recently recovered from infection
Live vaccine should not be given normally for 12 weeks
after giving normal human Ig and if already given
NHIg should be differed for 2 weeks
Eg : Hep A, Hep B, Tetanus, Rabies
Antisera and antitoxins
 They are materials prepared in animals ( horses)
 Passive immunization is achieved
 Eg: tetanus, snake bite, diphtheria
Cold chain
 It is the system of storage – transportation of vaccines
from the manufature to the actual vaccination site
 Polio is most sensitive to heat among vaccines requires
storage at -20 degree C.
 Vaccine stored in freezer compartment are polio and
measles
 Vaccine in cold part but never allow to freeze are ‘T’
series vaccine, DPT, TT,DT,BCG & diluents
 Vaccine should be protected from sunlight and anti
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septics
If refrigerated temperature is kept between 2 and 8
degree C vaccines (except polio) can be stored upto 5
weeks
Reconstituted BCG and measles are kept +2 to +8
degree C for max, of 4 hours and JE vaccine upto 2
hours
Return the unused vaccine vial to PHC from site on the
same day in cold chain
Discard vaccine that are unused more than 3 times
Cold storage equipment
(a)Walk-in cold room:
Located at regional level
meant to store up to 3 months
Serve 4 to 5 districts
(b) Deep freezer:
supplied to all districts (large) & PHC (small)
Cabinet temperature is -15 to -25 degree C
In case of power failures they can maintain cabinet
temperature upto 18 to 22 hours
At PHC level deep freezer are used only for ice pack
preparation and not for vaccine storage
( c) Ice lined refrigerator ( ILR):
Kept at district ( large) and PHC (small)
Cabinet temperature is maintained at +2 to +8
At PHC, ILR are used to store vaccines
ILR are lined with tubes or ice packs to maintain internal
temperature
ILR can keep vaccine safe with 8 hours of continuous
electricity supplied in a 24 hour period
They are top opening – can hold cold air inside better than
front opening
Vaccine kept in basket along with diluents
Keep spaces with boxes
 A dial thermometer is kept in ILR and temperature is
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recorded twice a day
In case of electric supply failure or during defrosting
vaccines transferred to cold boxes
DO’S - keep away from direct sunlight and 10 cm
away from wall ,
keep voltage stabiliser,
keep equipment levelled ,
keep space between vaccines for air circulation,
open only when necessary, defrost periodically
 DONT’S – Not to keep anyother equipments drugs
,food, water inside it
Discard expired vaccine
(d) Cold boxes :
Supplied to all peripheral centers
Used mainly for transportation of vaccines
Ice pack are placed at bottom and sides
Vials of DPT , DT , TT & diluents should not be placed in
direct contact with frozen ice packs
(e) Vaccine carrier:
Used to carry small quantities of vaccine ( 16 to 20 vials)
4 frozen ice pack are used for lining the sides
(f) Day carrier :
Used to carry small quantity (6 to 8 vials)
2 frozen ice packs are to be used
Used only for few hours
(g) Ice packs:
Only water is filled upto the level marked
If leaking discarded
-risk of cold chain failure is greatest at sub-centre level. Hence ,
vaccines are not stored there.
 Vaccine vial monitor(VVM)
 Adverse events following immunization(AEFI)
(a) Vaccine reaction
(b) Programme error
(c) Coincidental
(d) Injection reaction
(e) Unknown
--precautions to be taken
Contra indications of vaccine
 NIS- national immunization schedule
 UIP – universal immunization programme – infancy
 EPI – expanded programme on immunization – till 5
years
 Pulse polio immunization
 Catch up- keep up- follow up