Passive immunity is temporary protection transferred from another individual, such as maternal antibodies. Active immunity is stimulated through natural infection or vaccination and results in the formation of memory cells that provide long-lasting protection. Vaccines work by mimicking natural infections and stimulating the immune system to develop antibodies and memory cells against targeted pathogens. Widespread vaccination benefits both individuals and communities through herd immunity.

1. IMMUNIZATION
MAIGA AYUB HUSSEIN
Ms-Epidemiology, ADHSM, M&E,
GCP, BScN

2. PASSIVE AND ACTIVE IMMUNITY
• Passive Immunization
• Methods of acquisition include natural maternal
antibodies, antitoxins, and immune globulins
• Protection transferred from another person or animal
• Active Immunization
• Methods of acquisition include natural infection, vaccines
(many types), and toxoids
• Relatively permanent

3. Acquisition of Passive and Active
Immunity

4. Passive Immunization
• Can occur naturally via transfer of maternal antibodies
across placenta to fetus
•
• Injection with preformed antibodies
• Human or animal antibodies can be used
• Injection of animal Ab’s prevalent before vaccines
• Effects are only temporary
• The transfer of antibodies will not trigger the immune
system
• There is NO presence of memory cells

5. Active Immunization
• Natural Infection with
microorganism or artificial
acquisition (vaccine)
• Both stimulate the
proliferation of T and B
cells, resulting in the
formation of effector and
memory cells
• The formation of memory
cells is the basis for the
relatively permanent
effects of vaccinations

6. Herd Immunity
• Majority of population is immune, so chance of susceptible individual
contacting infected individual is low
E.G. Measles Epidemic.
• Factors affecting herd immunity
– Environmental Factors: crowded conditions, seasonal variations
– Strength of Individual’s Immune System
– Infectiousness of Disease: greater the risk of infection, the higher
percentage of people need vaccines to attain herd immunity
• When enough people are vaccinated, chance of germ infecting the non-
immunized population is small
• Can lead to disappearance of diseases (smallpox)
– Vaccination no longer necessary

7. Why is immunization important?
• From birth, a child should be immunized with
vaccines, which are either injected into the
body or given orally.
• Immunization helps protect the child against
infectious diseases that can cause illness or
death. These include: Tuberculosis,
Diphtheria, Whooping cough, Tetanus, Polio,
Hepatitis B, Haemophilus influenza,
Pneumonia, Measles and Rotavirus

8. CONT:
• At nine months, Vitamins A is given to the
child to ensure they develop strong immunity
against all diseases.
• All pregnant women and their newborns need
to be protected against tetanus. Even if a
woman was immunized earlier, she needs to
check with a trained health worker for advice
on tetanus toxoid immunization.

9. Immunization schedule for children
under one year

10. Here are the benefits of immunization
• It strengthens a child’s ability to fight diseases.
• It reduces the chances of children suffering from childhood immunisable
diseases.
• It protects children from liver disease and cancer of the cervix in girls, in
later years of their life.
• It prevents complications such as lameness and blindness in children.
• It reduces the burden/costs on parents/caregivers and communities in
terms of time and money spent on treatment. This contributes to socio-
economic development.
• It contributes to a child’s proper growth and development.
• It protects the entire community from childhood vaccine preventable
diseases.
• It protects the mother and her unborn baby from Tetanus.
• Once a child is immunized, he/she is protected against vaccine preventable
diseases for his/her entire life.
• Makes children healthy and strong to serve and fulfil their God given
purpose

11. VACCINE TYPES
• Whole-Organism
– Attenuated Viral/Bacterial
– Inactivated Viral/Bacterial
• Purified Macromolecules
– Polysaccharide
– Toxoid
– Recombinant Antigen
– Recombinant-Vector
• DNA
• Synthetic Peptide
• Multivalent Subunit

12. Vaccine Types

14. Live Attenuated Virus (LAV) Vaccines
• Live attenuated virus vaccines are based on
viruses that have been weakened in a
laboratory so that they do not proliferate well
in a host. This allows the host time to generate
an immune response in the absence of serious
disease. Since attenuated viruses most closely
resemble the wild pathogen, this type of
vaccine stimulates a strong immune response
and provides robust immunity.
• Bacillus Calmette-Guerin (BCG)

15. ADVANTAGES AND DISADVANTAGES
OF LIVE ATTENUATED VACCINE
• Prolonged immune-system exposure
• Single immunizations
• Replication within host cells
DISADVANATAGE
• MAJOR disadvantage is possible reversion
• ex: Rate of reversion of Sabin Polio vaccine is one case in 4 million doses
• Presence of other viruses as contaminants
• Unforeseen postvaccine complications

16. Inactivated (Killed) Antigen Vaccines
• Inactivated antigen vaccines contain killed
bacteria or inactivated viruses that cannot
proliferate. Since they contain all the chemical
motifs of the live pathogen, they stimulate the
adaptive immune system to react, but they
are not as effective as live attenuated vaccines
and require multiple doses. They are,
however, safer and more stable products.

17. Attenuation vs. Inactivation

18. Subunit and Toxoid (Inactivated Toxin)
Vaccines
• Subunit and toxoid vaccines do not contain
any microbes at all. The subunit antigen is a
protein or a carbohydrate found on the
surface of the pathogen. The immune system
is therefore triggered to just recognize that
one part of an invading pathogen. These
vaccines often require multiple doses to be
effective.

19. RNA-Based Vaccines
• RNA-based vaccines are a relatively recent
development, but they are the subject of significant
research interest due to their accelerated development
timelines relative to other vaccines.
• Scientists sequence the genome of a viral pathogen
and determine which sections code for proteins that
could make a good antigen.
• They then produce mRNA—genetic material that codes
for that protein—purify it, and formulate it as a
vaccine. On administration, the subject’s cellular
machinery translates the mRNA into the protein
antigen in vivo.
• An RNA-based approach is being used by several of
the groups developing COVID-19 vaccines.

20. Sources of Antigen
• Whole viral and bacterial antigens are grown in
highly controlled lab cultures and require
substantial purification.
• Sub-unit protein antigens are usually derived from
yeast cells that have been genetically modified.
• RNA is produced in a lab by advanced chemical
synthesis techniques and often encapsulated in
lipidic or polymeric particles to protect the
molecule within the body.

21. PHYSICAL BARRIERS PREVENTING
ENTRY OF PATHOGENS IN OUR
BODIES