Vaccinations - Basics

DR.PADMESH.V
PEDIATRICIAN,
AWACH.

 HISTORY OFVACCINATION:
429 BC
 Greek historianThucydides noticed that people
who survive smallpox did not get re-infected.

900 AD
 Chinese discover variolation
 Primitive form of vaccination
 Aim was to prevent smallpox by exposing healthy
people to tissue from the scabs of infected people.

1796 AD
 Edward Jenner discovers vaccination
 “The father of immunology“.
 His work is said to have "saved more lives than the
work of any other human"

1796 AD
 Noting that milkmaids who suffered the mild
cowpox never contracted smallpox, Jenner
experimented on several children, including his
own 11-month-old son.
 He inserted pus taken from pustule of Cowpox and
inserted it into an incision on childrens’ arm. Later
injected variolous material, but those children did
not get infected with small pox.

1798 AD
 The results were finally published and Jenner
coined the word Vaccine from the Latin 'vacca' for
cow.

1803 AD
 Royal Jennerian Institute founded

1880 AD
 RabiesVaccine developed by Louis Pasteur

1890 AD
 German scientist Emil von Behring discovered
the basis of diphtheria and tetanus vaccines.
 Awarded the first Nobel Prize in Physiology/
Medicine.

1920 AD
 Vaccines available againstTB, diphtheria,
tetanus, pertussis.

1980 AD
 Small pox eradicated from the world.

IMMUNITY
INNATE ACQUIRED
(GENETIC)

VACCINE (antigenic material)
Pathogens

 A vaccine typically contains an agent that
resembles a disease-causing agent.
 It is often made from weakened or killed forms of
the microbe, its toxins or one of its surface
proteins.
 The vaccine stimulates the body's immune
system to recognize the agent as a threat,
destroy it, and keep a record of it, so that the
immune system can more easily recognize and
destroy any of these microorganisms that it later
encounters.

 By priming the immune system by
vaccination, when the vaccinated
individual is later exposed to the live
pathogens in the environment, the
immune system can destroy them before
they can cause disease.

 Vaccines are of 4 types:
(i) Live attenuated vaccines: consist of live bacteria
or viruses which have been rendered avirulent.
(ii) Killed (Inactivated) vaccines: consist of
microorganisms killed by heat or chemicals.
(iii) Subunit vaccines: only the antigens that best
stimulate the immune system are included
(iv)Toxoids: are modified bacterial exotoxins so
that toxicity is lost but antigenicity is retained.

 (i) Live attenuated vaccines:

 ADVANTAGES:
 Excellent immune response that is nearly as good a
wild infection.
 Live microorganisms provide continual antigenic
stimulation giving sufficient time for memory cell
production.
 Attenuated pathogens are capable of replicating within
host cells  Cell mediated immunity possible.

 DISADVANTAGES:
 Can revert to original form and can cause disease.
 Harmful to immunocompromised patients.
 Not given in pregnancy.
 Less stable, most require strict cold chain.

 DISADVANTAGES:
 Can revert to original form and can cause disease.

 EXAMPLES.
 Varicella
 BCG
 Rota virus
 OPV
 MMR

 (ii) Inactivated (Killed) vaccines:

 ADVANTAGES:
 No live component  So will never cause disease.
 Safer than Live vaccines
 More stable than Live vaccines.

 DISADVANTAGES:
 May not always induce an immune response after the
1st dose.
 Immune response may not be long lived.
 Several doses of inactivated vaccines may be required
to evoke a sufficient immune response.

 EXAMPLES:
 Whole Cell Pertussis.
 Inactivated Polio

 (iii) Sub unitVaccines:
 Subunit vaccines, like inactivated whole-cell vaccines,
do not contain live components of the pathogen.
 They differ from inactivated whole-cell vaccines, by
containing only the antigenic parts of the pathogen.

 ADVANTAGES:
 No live components  Hence cannot cause disease
 Safer than Live vaccines
 More stable than Live vaccines.

 DISADVANTAGES:
 No guarantee that immunological memory will be
formed in the correct manner.
 Less immune response compared to Live vaccines.

 3 types:
1.Protein based
2. Polysaccharide
3. Conjugate

1.Protein basedVaccine
A specific isolated protein of the pathogen is used.
Disadvantage: If that protein is denatured, immune
response may be inadequate.
Eg: Acellular Pertussis (inactivated pertussis toxin
+ bacterial components)
Hepatitis B vaccine ( Hepatitis B surfaceAntigen
HBsAg )

2.PolysaccharideVaccine
Polysaccharide from cell wall of bacteria is used.
Disadvantage:
-T-cell independent (Stimulate B cells without
stimulating T Helper cells)
Poor immune response in < 2 years age
Only Short term immunity (No immune memory)
No booster response even after repeated injections

2.PolysaccharideVaccine
Examples:
- TyphoidVi PolysaccharideVaccine
- Pneumococcal Polysaccharide vaccine

3. ConjugateVaccine:
Polysaccharide from cell wall of bacteria is used
+
CARRIER PROTEIN
( Conjugation )
T Cell Independent  T Cell DEPENDENT immunity
1. Increased Immune response <2years age
2. Booster response to multiple doses

3. ConjugateVaccine:
Examples:
- Hib
- Pneumococcal ConjugateVaccines (PCV-10,13)

 (iv) Toxoid vaccines:
 Toxin is rendered harmless and used as the antigen in
the vaccine to elicit immunity.
 ADVANTAGES:
 Does not cause disease.
 DISADVANTAGES:
 Not highly immunogenic
 May require multiple doses

 (iv) Toxoid vaccines:
 Examples:
-TetanusToxoid
- DiphtheriaToxoid

 Question 1:
 I am scared about side effects of vaccine after
media reports.
 Answer:
 Serious side effects are extremely rare, and
mostly due to human error, rather than vaccine
itself.

 Question 2:
 My Child was immunised against this disease, yet
she got it.Why?
 No vaccine provides 100% protection.
The incidence is decreased drastically, and even if
the child gets the disease, it will be mild.

 Question 3:
 My Child has so many pending vaccinations. Can
they be given 1 week apart, so as to finish them
early?
 No.
Any number of vaccines can be given on the same
day.
However,if not given on the same day, a
minimum of 28 days interval should be
maintained before the next vaccination.

 Question 4:
 I missed giving my child a vaccine at the
recommended date. Should I start over all again?
 No.
Immune system has good memory function.
So no need to re-start schedule. Continue from
where you left it.

 Question 5:
 When I went to one pediatrician, I was told one
schedule.When I went to another doctor, I was
given another schedule.Which is the correct one?
 There are many schedules- National
Immunization Program,WHO program, and
IAP Recommendations.
Stick on to one schedule.
Also, recommendations keep changing.

 Question 6:
 Should I give the optional vaccines? Especially the
expensive ones?
 All optional vaccines should be given if
affordable.
They are effective.

 Question 7:
 What is ‘Painless vaccine’? Is it less effective than
the normal vaccine?
 DTaP is called the Painless vaccine.
Though efficacy is said to be almost the same, the
current recommendation is to use DPT, and not
DTaP.

 Question 8:
 What vaccine should be taken for Polio? OPV or
IPV?
 IPV is the current recommendation. However, if
IPV is not feasible, OPV can be given.
6,10,14 weeks  IPV
6 mth, 9 mth, 5 years  OPV

 Question 9:
 What is the schedule for Chicken pox vaccine?
 The current recommendation forVaricella is:
After 15 months of age  1st Dose
At 5 years  2nd Dose
(2nd dose can be given anytime 3 months after 1st
dose)

 Question 10:
 What is the recommendation regarding
pneumococcal vaccine?

 FREEVACCINATION REMINDER SERVICE:
SMS
<Immunize> <name> <date of birth>
to 566778

Vaccinations - Basics

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