The document provides a comprehensive overview of vaccines, including their history, principles, types, and modes of action. It outlines key advancements in vaccination, such as Edward Jenner's smallpox vaccine and Jonas Salk's polio vaccine, while detailing how vaccines work with the immune system to provide protection against various diseases. Furthermore, it categorizes vaccine types, including live attenuated, inactivated, subunit, conjugate, and mRNA vaccines, explaining their mechanisms and examples.

1. VACCINES- GENERAL
PRINCIPLE & TYPES
S u b m i t t e d B y : - M a y a n k K u m a w a t
S u b m i t t e d To : - D r. D e e p t i M a ’ a m
C o u r s e : - B S c ( H ) M B

2. Contents
2
History of Vaccine
Introduction to Vaccine
Immune system and Vaccine
General Principles of Vaccine
Vaccine types
Mode of Action

3. History of Vaccine
• In 1796, Edward Jenner developed the first true
vaccine by using cowpox to protect against
smallpox, a groundbreaking moment in medical
history.
• Jenner's discovery that the cowpox virus could be
used to protect against smallpox was a major
scientific breakthrough that laid the foundation
for modern vaccination.
• Polio was a devastating disease that affected
millions of people, particularly children, leaving
many with lifelong paralysis or even death.
• In 1955, Dr. Jonas Salk developed the first
effective polio vaccine, a landmark achievement
that transformed the fight against the disease.
3

4. Introduction
• Vaccine suspension of weakened, killed, or
fragmented microorganisms or toxins or
other biological preparation, such as those
consisting of antibodies, lymphocytes, or
messenger RNA (mRNA), that is
administered primarily to prevent disease.
• Vaccines are medical treatments that help
the body's immune system recognize and
fight off harmful pathogens like viruses and
bacteria. By exposing the body to weakened
or inactive forms of these threats, vaccines
stimulate the production of antibodies,
providing protection against future infection.
4

5. Immune System and Vaccine
• The human immune system is a complex network
of cells, tissues, and organs that work together to
defend the body against harmful pathogens.
Vaccines harness the power of the immune
system to provide protection against specific
diseases.
• By introducing weakened or inactivated forms of
a pathogen, vaccines stimulate the immune
system to produce antibodies and memory cells,
priming it to respond quickly and effectively if
exposed to the real threat.
5

6. Vaccine Antigens
1.Vaccine antigens are the key components that
stimulate the immune system to produce
antibodies and provide protection against a
specific disease.
2.Antigens can be derived from weakened or
inactivated forms of the pathogen, purified
proteins, or synthetic molecules that mimic the
structure of the pathogen.
3.The choice of antigen is crucial in determining
the effectiveness and safety of a vaccine, as it
must be able to trigger a robust immune response
without causing harm to the recipient.
6

7. General Principles of Vaccine
1. Pathogen Exposure: Vaccines expose the body to a harmless form of the pathogen or to antigens
that resemble the pathogen. This exposure triggers the immune system to produce an immune
response, including the production of antibodies and memory cells.
2. Memory Cells: Vaccines often stimulate the production of memory cells, which "remember" the
pathogen and enable a rapid and robust immune response upon subsequent exposure to the actual
pathogen.
3. Herd Immunity: Widespread vaccination not only protects vaccinated individuals but also helps
to protect unvaccinated individuals by reducing the spread of the disease within the community.
4. Booster Shots: Some vaccines require booster shots to maintain immunity over time. These
booster shots help reinforce the immune response and extend the duration of protection.
7

8. Types of Vaccine
1. Live Attenuated Vaccine
2. Inactivated Vaccine
3. Subunit Vaccine
4. Conjugate Vaccine
5. mRNA Vaccines
8

9. Live Attenuated Vaccine
• These vaccines contain weakened versions of the live
virus or bacteria. They stimulate a strong immune
response while posing a low risk of causing disease.
• Live attenuated vaccines contain weakened versions of a
virus or bacteria that can replicate in the body, but do not
cause the full-blown disease.
• They stimulate a robust immune response, similar to a
natural infection.
• The vaccine often provide long-lasting immunity with just
one or two doses, but carry a small risk of reverting to a
virulent form and causing illness in immunocompromised
individuals.
• Example of live attenuated vaccine - measles, mumps,
and rubella vaccine (MMR) and varicella (chickenpox)
vaccines.
9

10. Inactivated Vaccine
• These vaccines contain killed or inactivated forms of
the pathogen. They are generally safer but may
require multiple doses to build sufficient immunity.
• The Inactivated Viruses or bacteria cannot replicate in
the host body but still stimulate the immune system to
produce antibodies. This makes them a safer option,
especially for people with weakened immune system.
• Inactivated vaccines often require multiple doses and
may not provide as long-lasting immunity as live
vaccines . But they are a reliable choice for protecting
against diseases like influenza, hepatitis A, and polio
vaccine.
• Examples of Inactivated vaccine – Polio, hepatitis A,
and rabies vaccines.
10

11. Subunit Vaccine
• These vaccines contain only the essentials parts of
the pathogen, such as protein or sugars , to trigger an
immune response without causing illness.
• Subunit vaccines contain only specific part of
pathogen, such as proteins or polysaccharide, rather
than the whole organism.
• This targeted approach can trigger an immune
response without causing disease.
• Subunit vaccines are generally safer and more stable
than live vaccines, making them suitable for
immunocompromised individuals.
• Examples of subunit vaccine – influenza and
pneumococcal vaccines.
11

12. Conjugate
Vaccine
• Conjugate Vaccines link a weak antigen, often a
polysaccharide, to a stronger protein carrier. This enhances the
immune response, making conjugate vaccines highly effective
for preventing diseases caused by encapsulated bacteria like
haemophilus influenzae type b and pneumococcus.
• The protein carrier triggers a T-cell dependent immune
response, improving memory and boosting antibody
production against the polysaccharide antigen.
• Conjugate vaccines, in which capsular polysaccharides are
covalently bound to a protein-based carrier, are of particular
interest as they are highly effective in the prevention of
disease.
• Examples of conjugate vaccine – Hemophilus influenza type b
(Hib) vaccine, meningococcal group C conjugate (MnCC)
vaccine, pneumococcal conjugate (PnC) vaccine.
12

13. mRNA Vaccine
• An mRNA Vaccine is a type of vaccine that uses a copy of a
molecule called messenger RNA (mRNA) to produce an
immune response.
• mRNA vaccines are a novel type of vaccine that use
messenger RNA (mRNA) to instruct the body’s cells to
produce a specific viral protein. This triggers an immune
response, helping the body recognize and fight the actual
virus.
• mRNA vaccines are highly effective and can be rapidly
developed and scaled for mass production compared to
traditional vaccine technologies.
• The goal of a vaccine is to stimulate the adaptive immune
system to create antibodies that precisely target that particular
pathogen.
• Example of mRNA vaccine - Influenza (flu), Rabies, Zika
virus.
13

14. Mode of Action of Vaccine
1. Exposure to Antigen: Vaccines contain antigens, which are
substances that trigger an immune response. These antigens
can be weakened or killed forms of the pathogen (live
attenuated or inactivated vaccines), pieces of the pathogen
(subunit vaccines), or genetic material encoding antigenic
proteins (DNA or mRNA vaccines).
2. Activation of Immune Response: When a vaccine is
administered, the antigens it contains are recognized by the
immune system as foreign invaders. This recognition
activates the immune response, initiating a cascade of events
aimed at eliminating the perceived threat.
3. Antibody Production: One key aspect of the immune
response triggered by vaccines is the production of
antibodies. Antibodies are proteins produced by specialized
white blood cells called B cells. They bind to specific
antigens, marking them for destruction by other immune
cells.
14

15. 3. Cellular Immunity: In addition to antibodies, vaccines can also stimulate cellular immunity. This
involves the activation of T cells, another type of white blood cell. T cells play a crucial role in
directly attacking infected cells and coordinating the immune response.
4. Memory Response: One of the most important aspects of vaccination is the induction of
immunological memory. This means that after exposure to a vaccine, the immune system "remembers"
the pathogen and retains the ability to mount a rapid and robust response upon subsequent exposure.
Memory cells, including memory B cells and memory T cells, are generated during the initial immune
response and can persist for years or even decades, providing long-lasting immunity.
5. Protection Against Infection: The ultimate goal of vaccination is to confer protection against the
target disease. By priming the immune system to recognize and respond to specific pathogens,
vaccines help prevent infection or reduce the severity of illness if infection does occur. In some cases,
vaccines can also prevent transmission of the pathogen to others, contributing to herd immunity.
15

16. Thank You
16