immunization
TRANSCRIPT
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 RESPONSEA. 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 T-lymphocytes.
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,
pregnancyIf two live vaccine required – either given at two sites
simultaneously or with an interval of at least three weeksShould be properly storedUsually require only one dose , exception of polioEg: 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 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 : aluminiumphosphate, 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 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 +8At PHC, ILR are used to store vaccinesILR are lined with tubes or ice packs to maintain internal
temperatureILR can keep vaccine safe with 8 hours of continuous
electricity supplied in a 24 hour periodThey are top opening – can hold cold air inside better than
front openingVaccine kept in basket along with diluentsKeep spaces with boxes
A dial thermometer is kept in ILR and temperature is 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 markedIf 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