The document discusses vaccines, defining them as immunobiological substances designed to provide specific disease protection, and outlines various types including live attenuated, inactivated, toxoid, and DNA vaccines. It highlights the importance of the Expanded Program on Immunization (EPI) in Nepal, particularly regarding Oral Polio Vaccine (OPV) and Inactivated Polio Vaccine (IPV), and presents rationale for transitioning from OPV to IPV to mitigate risks of vaccine-derived poliovirus. Additionally, it discusses the benefits and risks associated with each vaccine type and their respective immunization strategies.

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Prepared by: Anish Dhakal (Aryan)
anishdhakal718@gmail.com
MBBS Student
Patan Academy of Health Sciences

2. OBJECTIVES
 To define vaccine
 To discuss the types of
vaccines
 To discuss the Expanded
Program on Immunization
(EPI) schedule of Nepal
with OPV and IPV rationale
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3. WHAT IS VACCINE?
 Vaccine is an immuno biological substance
designed to produce specific protection against
a give disease
 Artificial Active Immunity
 Triggers humoral and cell mediated immune
response or both mimicking the natural infection
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4. TYPES OF VACCINES
 Live attenuated vaccines
 Inactivated /Killed vaccines
 Toxoid vaccines
 Cellular fraction / sub unit
 Conjugate vaccines
 Acellular vaccines
 DNA vaccines
 Recombinant vaccines
 Combination vaccines
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5. LIVE ATTENUATED VACCINE
 Prepared from live (generally attenuated) organism
 Organisms lost pathogenicity but retain immunogenicity
due to repeated culturing
 More potent than other vaccines because:
 Resultant antigenic dose is higher and sustained
 Contain all major and minor antigenic components
 Engage body tissues causing persistent immune response
 Viral live vaccines are provoke excellent immune response
 Immunization usually with a single dose
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6. LIVE ATTENUATED VACCINE
 Example of live vaccines
include Measles, Mumps,
BCG, Influenza, Rubella and
oral polio vaccine
 Contraindication
 Immunocompromised state
(due to therapy or disease)
 Pregnancy
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7. INACTIVATED OR KILLED VACCINE
 Organism are killed by heat or
chemical and injected into body
 Usually safe, requires adjuvants
and less efficacious than live
vaccine
 Requires booster dose
 Examples include J.E , Rabies,
Hepatitis B, IPV
 Contraindication
 Severe local or general reaction
in previous dose 7

8. TOXOID VACCINES
 Toxins produce by organism
are detoxicated and used in
preparation of vaccine
 Antibodies produced
neutralized the toxin rather
than act upon the organism
 Toxicity is lost but antigenicity
is retained
 Examples – Diphtheria and
Tetanus
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9. CELLULAR FRACTION / SUB UNIT
 Conjugate vaccines
 Pieces from coats of bacteria are
linked to carrier protein which cause
immune response
 Example – Hib
 Acellular vaccines
 Vaccine that contain cellular material but
not complete cell
 Only those antigen/epitopes that evoke
best immune response are selected
 Example - Pertussis
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10. DNA VACCINES
 Genes for microbe’s antigen are introduced into
body, some cells take up the DNA
 Microbe’s DNA then instructs cell to synthesize
antigens
 The person’s own body become vaccine making
factories creating antigens required to provoke
immune response
 DNA vaccines being tested in humans include
those against the viruses that cause influenza and
herpes
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12. RECOMBINANT VECTOR VACCINES
 Similar to DNA vaccines
except use of a vector
 Use of attenuated and live
virus or bacterium to introduce
microbial DNA to the body
 Example – Hep. B , Cholera
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13. COMBINATION VACCINES
 More than one kind of
immunizing agent is
included in the vaccine
 It simplifies
administration and
reduces cost
 Example - DPT, DT,
MMR
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15. POLIO VACCINE: OPV VS IPV

16.  Routine immunization with OPV must cease after the
eradication of poliovirus because of the danger of
outbreaks of circulating vaccine-derived poliovirus and
the risk of VAPP (Vaccine Associated Paralytic
Poliomyelitis)
 In the regions of the world in which wild-type poliovirus has
been eliminated, moving to an IPV or IPV/OPV sequential
schedule will reduce or eliminate the risk of VAPP and
outbreaks of circulating vaccine-derived poliovirus, as well as
increase the likelihood of countries agreeing to stop
administering OPV after eradication is achieved.
 IPV could also be used with OPV in routine schedules to
increase immune responses and to decrease the circulation of
wild-type poliovirus in countries in which transmission has not
been stopped.

17. IPV – RATIONALE
 Type 2 poliovirus mutates into virulent form
 IPV contains killed virus, so IPV mitigates this risk
 IPV in addition to OPV provides better immunity
 All countries switched from tOPV to bOPV (minus type 2) 2016
 Introduction of IPV before this ensure protection against type 2
 Once virus circulation stopped everywhere, OPV withdrawn
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