Immunity
Development of (relative) resistance to infection acquired
passively/actively.
Passive
+From mother
+Transplacental
+Breast milk
+Administration of immunoglobulin
Active
+Natural infection
+Vaccine administration
Immunisation
Artificial induction of immunity by administering vaccine or
immunoglobulin.
Aim:
1)To prevent primary infection in the individual
(before exposure).
2)To break transmission of the infection &
control disease in community (herd immunity).
3)To eradicate disease.
Passive Immunisation
Administration of ready made antibody (human/animal) so as to prevent
infection.
Advantage: Immediate protection
Disadvantage:
Limited period
Protection not complete
Adverse reaction more
e.g. tetanus (for antenatal mother)
1) Heterologous (animal) antitoxin (AT)
+horse (equine) antisera
+e.g.
Dipteria AT
Botulism AT
+Allergic reaction more common/severe.
+Less protection than human AT.
2) Homologous (human) antibody
a) Human normal Ig
-pooled sera of donours with wide variety of antobody
(from natural infection & vaccination).
e.g. Measles Ig; Hep A Ig
b) Human hyperIg
-pooled sera of donours with known high titre of
specific antibody.
e.g. Hep B Ig; Varicella Zoster Ig; Human Tetanus
Ig; Rabies Ig
Active
Deliberate stimulation of an immune response against an infectious
disease by giving specific Antigen (vaccine).
Vaccine - An antigen (usually a protein) which stimulate the
body's immune system to produce antibody (humoral immunity) &
cell-mediated immunity against it.
1) Toxoid - inactivated toxin
e.g. Diphteria toxoid; Tetanus toxoid
2) Inactivated vaccine
a) Whole organism - killed
e.g. whole-ce ll pertussis vaccine; injectable polio
vaccine
b) Component vaccine
+purified immunogenic component
e.g. Hep B vaccine (surface antigen); acellilar
pertussis vaccine
+conjugqated to protein o make it more immunogenic
e.g. Hib (hemophilus influenza type B)
3) Live attenuated vaccine
-low virulence but still immunogenic
e.g. OBV
-related organism with shared organism
e.g. BCG; oral thyphoid vaccine
4) Synthetic vaccine
-recombinant DNA vaccine
e.g. recombinant Hep B vaccine
Adverse reaction to vaccination
-Local reaction
-Systemic reaction
True Contraindication
All Vaccines:
1. Acute illnesses
2. Anaphylaxis:
-to vaccine
-to vaccine constituents
Live vaccine:
1. Immunocompromised
-immunodeficient [congenital + acquired (HIV+)]
-immunosuppressives
-corticosteroids
-cancer chemotheraphy
-irradiations
-malignancies of RES
-malnutritions (severe)
2. Immunodeficient household contact
-e.g. oral polio vaccine --fecal oral route
transmission
3. Within 3 weeks of another live vaccine
4. Immunoglobulin (+ blood + blood product) --transfusion
-within 3 weeks before Ig (if hyperIg 6 weeks)
-withib 3-6 weeks after Ig
of Immunisation
[ 5. Pregnancy (esp 1st trimester) ]
Pertussis/DTP
1. Encephalpathy (within 7 days)
2. Hypotonic -- hyporesponsive episode (within 48 hours)
3. Screening attacks -- persistent inconsolable
crying > 3 hours (within 48 hours)
4. Seizures (within 3 days) -- afebrile fits
5. Progressive neurological disease/neonatal seizures
So, give only double immunisation on next schedule,
omitting pertussis
Not contraindication
1. Local reaction
2. Fever
3. Mild illness
4. Current antimicrobial theraphy
5. Topical/inhaled steroid
6. Prematurity/preterm
7. Underweight/undernourished
8. Neonatal jaundice
9. Mother pregnant
10. Child breast fedding
11. Personal h/o allergy/atopy
12. Family h/o allergy/atopy
13. Personal h/o febrile fits/epilepsy
14. Family h/o febrile fits/epilepsy
15. Recent/past h/o exposure to infection
16. Family h/o exposure to infection
17 Convalescing from illness
18. Unvaccinated household member
19. Past age of vaccination/too old
20. H/o chronic disease
21. History or presence of rash
22. Stable neurological condition e.g. epilepsy; spina bifida
Immunisation programme
-To reach all children before age of exposure to natural infection
-Initiation is a compromise between natural epidemiology of the disease
& maturing of tge immune system
-To maintain immunity with boosters
-Ongoing/routine
-Simple & easy to implement