VACCINOLOGY
Dr Noreen Shah
Principal Lecturer
Dept Of C. Med
Learning Objectives
At the end of this presentation the students shall be able to:
Describe the importance of vaccination in the control of infectious diseases
List the main types of vaccine with examples
Describe difference between live attenuated and inactivated vaccines
Describe the role of vaccines in preventing disease
Differentiate between vaccination and immunization
Describe Expanded Program of Immunization (EPI) of Pakistan
Describe the factors responsible for failure of vaccination programs in
Pakistan.
Define Immunity
The ability of an organism to resist
a particular infection or toxin by
the action of specific antibodies or
sensitized white blood cells.
The immune system is made up of different organs, cells, and proteins that
work together.
There are two main parts of the immune system:
The innate immune system, with which we are born.
The adaptive immune system, which develop when our body is exposed to
microbes or chemicals released by microbes.
1. The Innate Immune System
It is inherited and is active since birth.
It refers to nonspecific defence mechanisms that come into play
immediately or within hours of an antigen's appearance in the body.
These mechanisms include physical barriers such as skin, chemicals in
the blood, and immune system cells that attack foreign cells in the
body.
2. Acquired/adaptive Immunity:
It is the immunity which is developed later in life.
E.g. if an individual is infected with chicken pox virus, he/she become
resistant to same virus.
Acquired immunity is provided by Antibodies and certain T-lymphocytes.
These are specific to specific microorganism - therefore acquired immunity is
also known as Specific immunity.
Mechanism
Herd immunity
Herd immunity is a form of immunity that occurs when the vaccination of a
significant portion of a population (or herd) provides a measure of protection
for individuals who are not or cannot be immunized.
This can effectively stop the spread of disease in the community.
It is particularly crucial for protecting people who cannot be vaccinated.
These include children who are too young to be vaccinated, people with
immune system problems, and those who are too ill to receive vaccines (such
as some cancer patients).
The proportion of the population which must be immunised in order to
achieve herd immunity varies for each disease but the underlying idea is
simple: (once enough people are protected, they help to protect vulnerable
members of their communities by reducing the spread of the disease).
E.g. Herd immunity for measles is about 95% of people to be vaccinated
However, when immunisation rates fall, herd immunity can break down
leading to an increase in the number of new cases. For example, measles
outbreaks Pakistan.
Q: Does herd immunity work for all diseases?
No. Herd immunity only works for diseases that are spread directly between people (i.e. are
‘contagious’), like measles. One example where it would not work is tetanus
Q: How many children need to be vaccinated for herd immunity to work?
This varies depending on the germ and how contagious it is.
Q; Why is it important that children are vaccinated if they can be protected through
herd immunity?
For many diseases children, particularly young children, are at the highest risk of the disease
and also have the most severe illness. The best way to protect someone against a disease is to
vaccinate them directly, rather than rely on ‘indirect’ protection through herd immunity.
NAME:
Directions
Pick out 2 circles and mark them red.
Pick out 12 circles and mark them green.
Mark the rest blue.
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○○○○○○○○○○
○○○○○○○○○○
○○○○○○○○○○
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1. What percentage of this population is vaccinated? Use a proportion to find
out. 36/50 = n/100
2. What percentage of the group is unvaccinated? How can you find the answer?
Importance of vaccination in the control of
infectious diseases:
Vaccination is one of the most effective and cost efficient medical technology,
resulting in the control, elimination or near elimination of numerous
infectious diseases e.g. (small pox eliminated/polio is near for elimination)
Vaccines also protects from serious illness and death
It also prevent the outbreak of infectious diseases
Saves between 2 - 3 million children’s lives per year.
Today vaccines are available to protect against at least 20 diseases
However, one in five children still miss out on routine life-saving immunization.
Vaccines are required throughout our lives to help protect against serious
diseases.
Vaccines have greatly reduced infectious diseases that once regularly harmed
or killed many infants, children, and adults.
Vaccination is important because it not only protects the person who gets the
vaccine, but also helps to keep diseases from spreading to others, like family
members, neighbours, classmates, and other members of your communities.
Vaccine-preventable diseases have a costly impact, resulting in doctor’s visits,
hospitalizations, and premature deaths. Sick children can also cause parents
to lose time from work.
List of Types of vaccines with examples
Vaccine And Its Types:
A substance used to stimulate the production of antibodies and provide immunity
against one or several diseases. Prepared from the causative agent of a disease, its
products, or a synthetic substitute.
Treated to act as an antigen without inducing the disease.
There are 5 main types of vaccines.
1. Live Attenuated Vaccines:
Weakened form of the germ that causes a disease.
Create a strong and long-lasting immune response.
1 or 2 doses of most live vaccines give a lifetime protection.
Limitations:
As these are live vaccines cannot be given to immunocompromised people.
Rare risk of reversion to a virulent strain of germ.
They need to be kept cool.
EXAMPLES:
Influenza vaccine
i. Oral Polio Vaccine (OPV)
ii. Measles
iii. Typhoid oral
iv. Measles, Mumps, Rubella (MMR)
v. Yellow fever
OPV
vi. Hepatitis A
vii. Rota virus
viii. Intranasal influenza
ix. Typhus
2. Inactivated Vaccines
Are the killed version of the germ that causes a disease.
Usually do not provide immunity (protection) as strong as live vaccines.
So several doses may be needed over time (booster shots) in order to get ongoing
immunity against diseases.
Examples: Inactivated vaccines are used to protect against: Hepatitis A, Flu (shot
only), Polio (shot only), Rabies
3. Toxoid Vaccines
Toxoid vaccines use a toxin (harmful product) made by the germ that causes a disease.
They create immunity to the parts of the germ that cause a disease instead of the germ itself.
That means the immune response is targeted to the toxin instead of the whole germ.
Limitations: booster shots are needed
E.g. Diphtheria, Tetanus
4. Subunit vaccines
As compared to a whole-pathogen vaccine approach, a subunit vaccine will
only include certain components that originate from disease-causing bacteria,
parasites, or viruses.
These components (antigens) are highly purified proteins or synthetic
peptides that are considered to be significantly safer than whole-pathogen
vaccines.
There are three types of subunit vaccines
Protein based
Polysaccharide
Conjugate vaccines
A. Protein-based subunit /recombinant vaccines:
Protein based subunit vaccines present an antigen to the immune system
without viral particles, using a specific, isolated protein of the pathogen.
A weakness of this technique is that isolated proteins, if denatured, may bind
to different antibodies than the protein of the pathogen.
Examples: A cellular pertussis (aP), Hepatitis B
B. Polysaccharide vaccines:
These vaccines contain chains of sugar molecules (polysaccharides) found in
the cell walls of some bacteria.
Not be effective in infants and young children
Induce only short-term immunity
Examples: Pneumococcal, Meningococcal and Salmonella Typhi
C. Conjugate subunit vaccines
In comparison to plain polysaccharide vaccines, they benefit from a
technology that binds the polysaccharide to a carrier protein that can
induce a long-term protective response even in infants. bind a
polysaccharide chain to a carrier protein to try and boost the immune
response.
Example: Homophiles influenza type b (Hib) and Pneumococcal
conjugate vaccines
5. Nucleic acid vaccines
Use genetic material – either RNA or DNA
When this material gets into human cells, it uses cells' protein to make the
antigen that will trigger an immune response.
Advantages: Easy to make, and cheap.
As antigen is in large quantities, so the immune reaction is strong.
RNA vaccines need to be kept at ultra-cold temperatures, -70 C or
lower. Moderna vaccine is stored at minus 20° C
Challenges low- and middle-income countries that do not have specialised cold
storage equipment.
6. Combination vaccines
Combination vaccines consist of two
or more vaccines in the same preparation.
This approach has been used for over 50 years in many vaccines e.g. Pentavelant,
Hexavalent and MMR.
Combination products simplify vaccine administration and allow for the introduction
of new vaccines without requiring additional health clinic visit and injections.
Advantages of combination vaccines:
Reduce the cost of stocking and administering
Reduce cost of extra health care visits
Improve timeliness of vaccination (some parents and health-care providers
object to administering more than two or three injectable vaccines during a
single visit because of a child’s fear of needles and pain, and because of
concerns regarding safety)
Facilitate addition of new vaccines into immunization programs.
Quiz
A pregnant woman passes antibodies to her unborn baby through the placenta to protect against
certain diseases. About how long does this natural immunity last after birth?
A. 1 year
B. 2 years
C. 5 years
Bacterial meningitis strikes babies more often than any other age group. Which vaccine will help
prevent one previously common type of meningitis?
A. Tetanus
B. Hib
C. HIV
D. Varicella
Which diseases do the combined DTPa vaccines cover?
A. Diphtheria, Tuberculosis And Polio
B. Diphtheria, Tetanus And Polio
C. Diphtheria, Tetanus And Pertussis
D. Diphtheria, Tetanus And Pneumococcal Disease
E. Diphtheria, Tuberculosis And Pneumococcal Disease
Vaccine against viruses are usually:
A. Given at birth
B. Expansive
C. Either live attenuated or killed
D. Mainly polysaccrides
Routes of administration of different vaccines
Describe difference between live attenuated and inactivated vaccines
Features Live Attenuated Vaccines Killed Vaccines
1 Agent used Live attenuated organism Killed organism
2 Immune response High Low
3 Duration Antibodies persists for long time Short time
4 Booster Immunization Booster not needed Boosters needed frequently
5 Adjuvant Not required Required
6 Cold chain Required Not required
7 Cost Cheap Costly
8 Safety Chance of reversal Safe
9 Production Easy to produce Difficult to produce
The Expanded Program On Immunization (EPI)
Objectives of EPI
To affirm the commitment of the Government of Pakistan to provide safe, effective and cost-
effective vaccination against vaccine preventable diseases
To set national standards and guidelines for immunization aligned with the global goals and
evidence base
To encourage the generation of local evidence for vaccination against vaccine preventable
diseases
To increase equitable coverage of immunization services against vaccine preventable diseases
To decrease vaccine preventable diseases associated morbidity and mortality
To improve immunization services through expansion of service delivery and cold chain
• The Expanded Programme on Immunization (EPI) was launched in Pakistan
in 1974
• The Aim was to protect children by immunizing them against childhood
tuberculosis, poliomyelitis, diphtheria, pertussis, tetanus and measles.
• Later, with the support of development partners, a number of new vaccines
e.g. hepatitis B, haemophilus influenzae type b (Hib) and pneumococcal
vaccine (PCV10) were introduced in 2002, 2009 and 2012, and inactivated
polio vaccine in 2015, respectively.
• Rotavirus vaccine was introduced in 2017 prevent against fatal diarrhoea due
to rotavirus.
The Pakistan EPI programme has adopted its goals and strategies in accordance with
priorities set at the global and regional level.
EPI was launched in Pakistan in 1978 to protect children by immunizing them against
childhood tuberculosis, poliomyelitis, diphtheria, pertussis, tetanus and measles.
It also aims to protect mothers and new-born against tetanus.
Later hepatitis B, haemophilis influenza type b (Hib) and pneumococcal vaccine
(PCV10) were introduced in 2002, 2009 and 2012, respectively.
Inactivated polio vaccine (IPV) was added in 2015.
Rotavirus vaccine was introduced in 2017in EPI schedule.
A child needs only 5 visits during the first year and one visit during the second
year of life to complete the vaccination with 6 visits against 9 dreadful
diseases.
The National Immunization Technical Advisory Group (NITAG), was
established in 2008, by the Ministry of Health in accordance with WHO
guidelines.
A programme policy document was developed in 2015 with the support of
partners.
The document lays out policy direction and guidelines for involvement of lady
health workers and private sector in immunization service delivery.
The key goal of new immunization policy Pakistan’s Vision 2025 is - to
reduce infant mortality rate from 74 to less than 40/1000 births & reduce
maternal mortality rate from 276 to less than 140/1000 births and continue
reducing the infant mortality rate through immunization targets and activities in
order to achieve SDG 3
Diseases covered by EPI
1. Poliomyelitis
2. Childhood Tuberculosis
3. Neonatal Tetanus
4. Diphtheria Penta valent Vaccine
5. Pertussis (Whooping Cough)
6. Hepatitis-B
7. Haemophilus influenzae type b
8. Measles
9. Rota virus diarrhoea
Vaccine No. of Administration site Age Dose/ Storage temp
doses time
BCG 1 Vaccine is given Soon after birth 0.05ml + 2 to +8 ° C
intradermal on right At birth
deltoid
OPV 4 Orally 1st soon after 4 doses 1st - 15 to - 25 °C
birth 2nd 4 wks. year of life at federal level
3rd 10 wks. + 2 to + 8 ° C at
4th 14 wks. district level
Pentavelan 3 Deep IM at 1st 6 wks. 0.5 ml + 2 to + 8 °C
t+ anterolateral aspect 2nd 10 wks.
Pneumococ right thigh 3rd 14 wks.
cal
Vaccine No. of Administration site Dose Dose/ Storage
doses time temp
Measles 2 Subcutaneous 9 month 0.5 ml +2 to +8 °C
15 month
Hepatitis B 3 Deep IM – anterolateral aspect 1st 6 wks. 0.5 ml +2 to +8 °C
of left thigh 2nd 10 wks.
3rd 14 wks.
Rota virus 2 Orally – least 4 wks. apart 1 ml +2 to +8 °C
IPV 1 Deep IM at anterolateral aspect 14 wks. 0.5 ml +2 to +8 °C
of left thigh
Diarrhea Virus Diarrhoea 2 Rota 1: 6 /2 : 10 weeks
COLD CHAIN
Vaccines are sensitive biological products that may become less effective or
destroyed, when exposed to temperatures outside the recommended range.
Cold chain refers to the process used to maintain optimal conditions during
the transport, storage, and handling of vaccines.
Starting at the manufacturer and ending with the administration of the
vaccine to the client.
The optimum temperature for refrigerated vaccines is between +2°C and
+8°C.
Cold chain
Temperature monitoring devices
1. Cold Rooms and Freezer Rooms
2. Refrigerators and Freezers: Data loggers and dial thermometers
3. Transportation in Cold Boxes and Vaccine Carriers
4. Electronic freeze indicators
5. Cold Chain Monitor
6. Vaccine Vial Monitor
7. Electronic Shipping Indicator.
Cold room Cold boxes
EPI vaccines are placed in different compartments of refrigerator
Sensitivity of vaccines to heat and freezing
Vaccines Are Grouped Into Six Categories
The most heat sensitive vaccines are in group A and the least sensitive in group F.
Group A: OPV
Group B: Influenza
Group C: IPV, Measles/ Measles-rubella/ Measles-mumps-rubella (Freeze-dried)
Group D: Cholera, Hexavalent, Pentavalent, Hib (Liquid) Measles (Freeze-dried) Rotavirus
(Liquid And Freeze-dried) Rubella (Freeze-dried) Group E: BCG, Tetanus, TD, Td
Group F: Hepatitis B Hib (Freeze-dried), Meningococcal A, Pneumococcal
Sensitivity to freezing Sensitivity to light
Cholera
Vaccines that are as sensitive to light
Hexavalent as they are to heat include
Pentavalent
BCG
Hepatitis B
Hib (liquid) Measles
Inactivated poliovirus (IPV) Measles-rubella
Influenza
Measles-mumps-rubella
Pneumococcal
Rubella
Rotavirus Tetanus, DT, Td
EFFECTIVE COLD CHAIN
Three main elements combine to
ensure proper vaccine transport,
storage, and handling.
Transport Efficient
Trained
and storage management
personnel
equipment procedures
Electronic freezer/fridge indicator
These are irreversible temperature indicators
that shows if a vaccine has been exposed to
freezing temperatures.
It consists of an electronic temperature
measuring circuit and LCD-display.
lf the vaccine is exposed to a temperature
below - 0.5°C ± 0.5°C for more than 60min
the display will change from the "OK" status
symbol (✓) into the "ALARM" status symbol
(x).
A small blinking dot in the right-hand corner
of the LCD-display indicates that the device is
functioning.
Vaccine Vail Monitor
Vaccine Vail Monitor (VVM) is a thermo chromic label on vials containing vaccines.
It gives visual indication of whether the vaccines has been kept at a temperature
which preserves its potency.
The vials are designed in response to problem of delivering vaccines to developing
countries where.
i. Cold chain is difficult to preserve and,
ii. Vaccines became inactive and denatured by exposure to ambient temperatures.
Failure of Vaccination Programs in Pakistan
Factors Responsible for Failure of Vaccination
Programs In Pakistan.
Immunization is one of the most successful public health initiatives in recent
times. It is, therefore, worrying to learn the level of under-vaccination in
Pakistan.
Diseases that have been successfully eliminated through the aid of vaccination
in other countries have not been eliminated in Pakistan.
The reasons for this vary and show the uniqueness of the economic,
healthcare and environmental landscape of Pakistan, through which public
health programmes need to be implemented.
When compared to globally standardised targets for immunization, Pakistan is trailing behind.
Not achieving these targets is worrying from both a global perspective and within the national
healthcare landscape of Pakistan.
Research is necessary to bring together findings on the failings of routine immunization and polio
campaigns
The “Expanded Programme of Immunization” (EPI) is the main programme through
which routine immunization is provided to the public.
Within Pakistan, it has encountered many problems since its inception. These
includes
i. Logistical obstacles
ii. Parental and female awareness and education
iii. Influence of religious community leaders
iv. Conflict and war
v. Reduced focus on EPI funding and technical assistance in relation to
specific campaigns like polio
vi. Poor capacity of human resources has contributed significantly to its poor
performance.
These reasons include
o Poor worker motivation
o Political interference
o Underutilization of available human resources
o Worker fatigue due to polio and other regularly conducted campaigns have reduced the time
available for EPI
o Theft by workers
o Obstacles in procurement of vaccines and other required items
o Lack of proper cold chain monitoring
o Poor maintenance of equipment
o Inability to pay transportation and/or other costs
o Lack of available time during immunization hours, often due to other obligations to support
the family livelihood and traditions.
o Poor or disrespectful treatment from health workers during service contacts
Recommendations
The EPI needs drastic changes to improve its performance.
Interprovincial coordination and collaboration needs to be strengthened.
A situational analysis of the EPI should be carried out in each of the Provinces.
This assessment could include coverage, mapping of difficult-to-reach
populations and fixed service points.
The available human resources, logistical demands, funding, and demand
aspects of the program should also be included.
EPI implementation plan for each district within each province to consider
and address program gaps identified by the situational assessment.
The responsibility for planning should be delegated to the union council (UC)
and district-level staff under the direction of the provincial EPI manager.
This ensure ownership of the program, use local knowledge, and help to make
more realistic estimates of eligible children.
Integration of immunization services with maternal and child health (MCH),
integrated management of childhood illnesses (IMCI) programs
Integration of immunization with primary health care
Integration of immunization services with the private sector
The province should develop a comprehensive plan to expand the number of
fixed centres to cover all communities with a reorganization of outreach
services to address hard-to-reach areas, especially in high-risk districts.
The logistics system should be improved.
VVM and cold chain monitoring tools should be introduced
Vaccine procurement capacity and cold chain equipment maintenance as
well as back-up power systems are all in need of improvements.
Leadership and good management should be fostered through training.
Regular training of managers (Funding for this course to be offered
regularly in each province should be sought either from the Government
of Pakistan or from development partners).
Supervision and monitoring should be restructured. All categories of staff
should be encouraged to prepare monthly plans for supervision beforehand,
and seek pre-approval at the monthly conference of EPI staff.
Managers at all levels must closely monitor the completion of supervision by
lower-level by on-site spot checks on the staff
Monitoring, evaluation, and surveillance system of the EPI needs to be
strengthened.
