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IMMUNZ2
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ImmunizationAmha Mekasha, MD, Msc
DPCH
June 2012
Session objectives
• Define types of immunity
• Describe types of vaccines
• List contraindications of vaccinations
• Identify adverse effects following immunization
• Describe cold chain in immunization
• Define some key concepts in vaccination management
Under 5 Deaths from Vaccine Preventable Under 5 Deaths from Vaccine Preventable Diseases - 2002Diseases - 2002
Others = Polio, YF, Hep.B, Jap encep, Meningococcal
Over 2 Over 2 Million Million
Deaths to Be Deaths to Be PreventedPrevented
Passive & active immunity
natural immunity artificial immunity
post- infection
active
maternal antibody
transfer to the fetus
passive
exposure to antigen
active immunisation
active
injection of antibodies
passive immunisation
passive
Passive immunisation
antibody donor(immune subject)
antibody recipient(non-immune subject)
antibody transfer
Passive immunisation
anti
bod
y co
nce
ntr
atio
n
weeks4 8 12 16 20
injection of Ig
• short-term protection
• potential safety concerns
Vaccination
antigen (vaccine)administered to non-immune subject
actively immunised subject
Active immunization
anti
bod
y co
nce
ntr
atio
n
weeks4 8 12 16 20injection of vaccine
• long-term protection
• cost-effective
• safe
• is affordable & accessible to all
• has an acceptable reactogenicity profile
• is immunogenic and protective
• provides long-lasting protection
• does not require frequent boosters
• can be integrated into EPI
• is stable in field use
The ideal vaccine ….
• reduces morbidity & mortality• is a cost-effective intervention• protection of the individual• protection of communities (herd immunity)
• control of disease• elimination of diseases• eradication of disease & the pathogen
Benefits of vaccination
Benefits of vaccination
20
40
60
1980 1990 2000
polio - worldwidere
po
rted
ca
ses
(000
s)
EPI implemented
1950 1960 1970 1980
measles - US
vaccine introduced
20
40
60
1940 1950 1960
Diphtheria – England & Wales
rep
ort
ed c
ase
s (0
00s
)
vaccine introduced
Types of vaccines
• live-attenuated vaccines– polio Sabin (OPV), measles, mumps, varicella,
yellow fever, – BCG, cholera, typhoid fever ….
• killed, inactivated vaccines– polio Salk (IPV), hepatitis A, whole cell
pertussis (Pw) ….
Types of vaccines
• sub-unit vaccines– diphtheria, tetanus, pertussis toxoids– purified acellular pertussis (Pa) components– genetically engineered HBsAg, HPV, malaria– polysaccharides (Vi, Men, Pneumo) – conjugated polysaccharides (Hib, Men, Pneumo)– split or sub-unit influenza vaccines H1N1,
H3N2 (H5NI)
Types of vaccines
• combined vaccines– DTPw-HepB (Tetra); DTPw-HepB/Hib (Penta)– DTPw-HepB/Hib-MenAC (Hepta)– DTPa-HepB-IPV/Hib– Hib-MenC; Hib-MenCY; Hib-MenAC(W?)– Men ACWY polysaccaride vaccines– MenACWY conjugate PS vaccines– HepA/Vi; HepAHepB ….
Live-attenuated vaccines
strain attenuation in cell culture
wild virus replication in unfavourable conditions
the process is repeatedmany times …
… to produce an attenuated strain, unable to cause disease
Live-attenuated vaccines
attenuated virus from the Master Working Cell Bank …
is replicated on a
large scale
then harvested, tested, and formulated into a vaccine
Live-attenuated vaccines
disadvantages• may retain some pathogenicity
• may revert to virulence
• may not be safe enough to vaccinate highly immuno-compromised subjects
• require a good cold chain
Live-attenuated vaccines
advantages
• mimic natural infection• produce a large antigenic stimulus• generally induce T&B lymphocyte responses• provide long-lasting protection
Killed, inactivated vaccines
the pathogen is grown under suitable conditions
purified and treated with heat or chemicals
… so that it is inactivated but still immunogenic
Killed, inactivated vaccines
disadvantages
• often less effective than live-attenuated vaccines
• several doses needed for long-termprotection
• repeat administration may increase reactogenicity
• limited production capacity & higher price
Sub-unit vaccines
toxoid production
inactivation
antigenic determinantscapable of inducing an immune response
toxic groups
toxin
toxoid
Sub-unit vaccines
Purified antigenic extractsacellular pertussis vaccine components
• pertussis toxoid (excreted)
• filamentous haemagglutinin (excreted)
• pertactin (69 kDa outer membrane protein)
• fimbrial antigens
polysaccharides
• T-cell independent Ags• not immunogenic in infants• do not induce an immune memory (no booster effect
Sub-unit vaccinesconjugated polysaccharide vaccines
conjugated PSs
• T-dependent Ags
• immunogenic in infants as of 6 weeks
• establish immune memory• strong booster effect
Sub-unit vaccinesrecombinant HBsAg vaccines
isolation of HBV in the 1970s
isolation of the surface antigen gene
insertion of the gene into bakers’ yeast and HBsAg expression
Sub-unit vaccines
multiplication of yeast cells in fermentors
the yeast cells produce surface antigen
isolation & purification of the surface antigen particles
Adjuvants
anti
bod
y co
nce
ntr
atio
n
weeks2 4 6 8 10vaccination
primary response in the absence of adjuvant
+ adjuvant
Methods of administration
subcutaneous intramuscular
intradermaloral
Adverse reactions
• local reactions– pain at injection site, redness
– swelling
• systemic reactions– fever, malaise ...
vaccine Reaction Onset interval
BCG Lymphadenitis, Ostities, Disseminated BCG
2-6 mos1-12 mos1-12 mos
HepB Anaphylaxis 0-1 hr
MMR Febrile seizure,ThrombocytopeniaAnaphylaxisEncephalopathy
6-12 hrs15-35 days0-1 hrs6-12 days
OPV Paralytic polio 4-30 days
Tetanus Brachial neuritisanaphylaxis
2-28 days0-1 hr
DPT Seizurehyptonic hyporesponsive episodesAnaphylaxisEncephalopathypersistent inconsolable screaming >3 hrs
0-2 days0-24 hrs0-1 hr0-2 days0-24 hrs
Contra-indications• Hypersensitivity
• Symptomatic HIV infection (BCG)
• Pregnancy (except for vaccination against neonatal tetanus)
A network of refrigerators, cold stores, freezers and cold boxes organized and maintained so that vaccines are kept at the right temperature to remain potent during orders, supplies, transportation, storage, distribution to the point of
administration to the target population.
Cold chain
Storage and distribution
live-attenuated vaccines
• vaccine (but not diluent) can be stored in a freezer or at +2°C to +8°C
• after reconstitution, use as soon as possible; discard after 6 hoursor at the end of the session
Cold chain
• some vaccines are cryostable (stable if frozen)
• some vaccines are cryolabile (unstable if frozen)
• most vaccines are thermolabile (unstable if exposed to temperatures above +2°C to +8°C)
• some vaccines are more thermostable than others (DTP > measles > OPV)
Arranging Vaccine - 1Arranging Vaccine - 1
Correct use of upright refrigerators
Unplanned Storage capacity needsUnplanned Storage capacity needs
• Never freeze BCG if the diluent and the vaccine are packed together
• Freezing causes damage to: DPT-HepB-Hib, TT, inactivated polio, HepB.
Definition of some key concepts
• Coverage: is the percentage of immunized individuals among the target population
• Drop out: The drop-out rate is a comparison of number of children who start the immunisation schedule and the number who complete it.
• Access: First contact with the regular immunization service (DPT1)
• Missed opportunities: Failure to provide all antigens to the child or woman of child bearing age for which he/she is eligible
Drop-out rate: calculation
DTP1 – DTP3 drop-out rate:
cumulative doses of DTP1 - cumulative doses of DTP3 x 100
cumulative doses of DTP1
DTP1 – Measles drop-out rate:
cumulative doses of DTP1 - cumulative doses of measles
cumulative doses of DTP1x 100
• Ensure continuous supply of vaccines• Rescheduling of cancelled clinics where possible• Reduce waiting time• Client education
– Number of doses – Dates for return– Possible side effects
• Establishing a system for defaulter tracing involving both HWs and Community members.
REDUCING DROP OUTS
Calculating vaccination coverage by antigen/vaccine
CR = CR = Doses administered for a Doses administered for a vaccinevaccine x 100 x 100
target populationtarget population
• Ensure screening at every opportunity• Ensure children/mothers have immunization cards to
make screening easier
• Give all vaccines due whenever a child presents
• Eliminate all false contraindications
Preventing Missed Opportunities
Thank you
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