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Immunization Specific defences : Micro organism-breach local defense systemshost recognize, destroy and eliminate antigenicmaterial foreign to its ownSpecific defenses are 1.Active immunity humoral, cellular , combined immunity2.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 diseasesActive immunity may be acquired by following :-clinical infection-sub clinical or in apparent infection-immunization with an antigen THE IMMUNE RESPONSEPrimary response:-Ag first time administer IgMAb -----IgGAb-Nature and extend of primary response to anAg is determined by factors like -Dose of Ag, nature of Ag, route ofadministration, 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 antibodyResponse to booster dose differs in a no. of ways from primary responseProduction of Ab more rapidAb response maintained at higher level for a long period of timeAb tends to have a greater capacity to bind to Ag Humoral immunityIt comes from B cells (bone marrow derived lymphocytes) which proliferate and manufacture specific Ab after Ag presentation by macro phagesImmunoglobulin's are divided into 5 classes IgG, M,A,D &E .they circulate in body and neutralizes the microbes/toxinsAb are specific- they react with same Ag when provided Cellular immunitySome 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 bothIn some cases they jointly helps in immunityVaccine to be effective must ellicit both cell mediated and humoral responses

Active immunity takes time to develop . It is superior to passive immunity because duration of protection is long lastingWith few exceptions severe reactions are rare Protective efficiency is better than passiveActive is less expensivePassive immunity Ab produced in one body ( human / animal ) are transferred to another to induce protection against diseaseThat is, they are ready made AbPassive immunity may be induced by Ig or anti serum administration Ab through placenta , human milk (IgA)Passive immunity differ from active immunity by Immunity is rapidly establishedImmunity produced is only temporary ( days to months ), till when Ab is eliminated from the bodyThere is no education of RES

Herd immunityIt 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 immunityOccurrence of clinical or sub-clinical infection in herdImmunisation of the herdHerd structureIf herd immunity high enough , occurrence of epidemic is highly unlikelyHerd immunity is maintained by immunisation Eg: polio , diphtheriaWith no vaccine for small pox herd immunity is declinedImmunising agentsVaccines- substances-designed to produce specific protection against a given diseaseIt stimulate production of protective Ab Live vaccine (attenuated )Prepared from live organisum . Doesnt 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 vaccineVirus is killed with heat or chemicals and infected into the body to stimulate active immunityThey are usually safe but less efficacious than live vaccinesUsually require more than two to three primary and even a booster dose to produce adequate Ab responseUsually administered i/m or s/cOnly severe C/I is severe local or general reaction to previous doseEg: pertusis , IPV, typhoidToxoid:Exotoxins produced by certain organisum are detoxicated and used to prepare vaccinesThese Ab produced neutralises the toxin moiety produced during infection and not the organismHighly efficacious and safeEg : tetanus and diphtheria

Cellular fraction:Prepared from extracted cellular fractions like cell wall, capsule etcEfficacy and safety highEg : meningiococcal, pneumococcal

Combination:Simplify administration, reduce cost, minimise no. of contact of patient with health systemEg : DPT , MMR, Pentavalent Polyvalent : prepared from two or more strains of same species . Eg : polio infuenzaAutogenous vaccine : organism in vaccine is obtained from the same patientVaccine can be plain , adjuvant , freeze dried preparationAdjuvant is added to vaccine with an intent of potentiating the immune response.eg : aluminium phosphate, aluminium hydroxideFreeze dried vaccines ( BCG , Measles , YF) are more stable preparations than liquid vaccines

ImmunoglobulinComposed of five major classes and its sub units- IgG,M,D,A,EIg preparations : two typesNormal human IgSpecific human Ig usually made from plasma of patients who have recently recovered from infectionLive vaccine should not be given normally for 12 weeks after giving normal human Ig and if already given NHIg should be differed for 2 weeksEg : Hep A, Hep B, Tetanus, RabiesAntisera and antitoxinsThey are materials prepared in animals ( horses)Passive immunization is achieved Eg: tetanus, snake bite, diphtheriaCold chainIt is the system of storage transportation of vaccines from the manufature to the actual vaccination sitePolio 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 septicsIf refrigerated temperature is kept between 2 and 8 degree C vaccines (except polio) can be stored upto 5 weeksReconstituted BCG and measles are kept +2 to +8 degree C for max, of 4 hours and JE vaccine upto 2 hoursReturn the unused vaccine vial to PHC from site on the same day in cold chainDiscard vaccine that are unused more than 3 timesCold storage equipment(a)Walk-in cold room:Located at regional level meant to store up to 3 monthsServe 4 to 5 districts(b) Deep freezer:supplied to all districts (large) & PHC (small) Cabinet temperature is -15 to -25 degree CIn case of power failures they can maintain cabinet temperature upto 18 to 22 hoursAt 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 dayIn case of electric supply failure or during defrosting vaccines transferred to cold boxesDOS - 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 periodicallyDONTS Not to keep anyother equipments drugs ,food, water inside itDiscard expired vaccine

(d) Cold boxes :Supplied to all peripheral centers Used mainly for transportation of vaccinesIce 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)Vaccine reactionProgramme errorCoincidentalInjection reactionUnknown--precautions to be takenContra indications of vaccineNIS- national immunization scheduleUIP universal immunization programme infancyEPI expanded programme on immunization till 5 yearsPulse polio immunizationCatch up- keep up- follow up