Vaccines PY367

What is smallpox?

• Variola virus

• Highly contagious and plague causing

• Blistering rash, blindness and arthritis

• Mortality 30-50%

What is cowpox?

• Vaccinia virus but causes milder infections

• Edward Jenner noticed milkmaids who contracted it would not get smallpox

• He inoculated a boy with it and that boy did not have a reaction afterwards when exposed to smallpox

What is individual protection?

Vaccinating an individual and protecting them from infectious diseases which cause significant harm

What is community protection?

• Vaccinated individuals are less threat to other people so disease cannot spread = outbreaks reduced

• More people vaccinated = higher likeliness of eradicating disease from that community = Herd protection

What does the % required to achieve herd immunity depend on?

How virulent the virus is

Why can’t we vaccinate everyone against infectious disease?

• Countries may not be able to afford supplying everyone

• There is not a vaccine for every disease

• Vaccine hesitancy

What is the JCVI and what do they do?

• Joint committee on vaccination and immunisation

• Responsible for monitoring and updating vaccine schedule - triage system for vaccine order

• Recommend to government about all matters regarding vaccination

• Publish and update “green book”

How are groups targeted according to NHS schedule?

• Susceptibility and risk to a disease

• You may be susceptible to a disease but there may not be a risk to you if you get it

What 3 factors do the JCVI take into account when deciding?

1. Susceptible populations

2. Diseases themselves

3. Pharmaceutical issues and vaccine products

Explain susceptible population

• Age - babies lack immunity, old people immunity declines

• Risk category - some people have higher risk

• Social changes - starting school or uni

• Public/media campaigns/new research

Explain diseases themselves

• Prevalence of organisms and environmental factors

• Sudden outbreaks of disease

• Desire to increase herd immunity

• Prevention of other risks related to the disease

Explain Pharmaceutical issues and vaccines products

• Cost of manufacturing vs. Effectiveness of vaccine programme

• Antigenic shift/drift meaning new strains become prevalent

• If vaccine product is able to be produced

• Sometimes need to produce vaccine quickly due to outbreaks

What are vaccination risks?

• Mild fever, illness, rash

• Pain, swelling, tenderness at injection site

• Small anaphylaxis risk

• Can be related to excipients or antigen

What are vaccination benefits?

• Saves lives

• Herd immunity for those who cannot be vaccinated or are more vulnerable

• Eliminates diseases in some cases

• Better than contracting disease and treating it

What is the global situation?

• WHO monitors vaccination use globally

• Schedules may vary according to geographical area

• Access to vaccination is a health inequality problem

How did Jenner’s method work?

• First demonstration of cross protection using related, live virus

• Antigen on cowpox induced memory cells

• Upon future infection, memory cells secrete Ab which protect against both poxes

What is plan A of immune defence?

Block infection by utilising barriers to entry (tears, skin, stomach acids, mucus)

What is plan B of immune defence?

• Destroy invaders with innate IS

  • Cellular factors, complement, NK cells, Phagocytic cells

• If that fails, activate adaptive IS

  • APC’s with pathogen antigen fragments in MHC activate T helper cells which induce antigen specific CTL’s and B cells

What is active acquired immunity?

• Produced by individuals own IS

• Involves cellular responses and humoral responses or combo of both

• Can be acquired by disease or vaccination

• Vaccines provide immunity similar to that provided by natural infection without its complications

What do T helpers do?

Enable other immune responses such as CTL and B cells for Ab

What do B cells do?

Make Ab which can block virus from infecting cells as well as mark it for destruction

What do cytotoxic T cells do?

Identify and destroy virus infected cells

What do vaccines do to APC?

Replace displayed portion with vaccine to activate same mechanism without SE from actual disease

What is Ab mediated immunity?

1. Ab blocks binding of pathogens to cell surface receptors

2. Cytotoxic lymphocytes - CD8+ cells target infected cells (antibody dependent cellular cytotoxicity ADCC)

3. Pathogens are coated and tagged for phagocytosis

4. Ab-antigen complexes will activate classical complement cascade which leads to pathogen destruction by phagocytosis or bacterial membrane attack

What are 3 Ab subtypes?

1. IgM

2. IgG

3. IgA

What do each of the immunoglobulins do?

• IgM - complement activation

  • Induced by vaccination

  • Limited role

• IgG - systemic

  • All major roles like neutralisation, ADCC, opsonisation and complement activation

  • Primarily induced by vaccines and main ones we want to induce

• IgA - principle isotope in secretions at mucosa

  • Strong viral neutraliser but weaker at the others

  • Can be induced by vaccines but needs special route

What is passive acquired immunity?

• Protection by transfer of Ab from mother across placenta (IgG) and breast milk (IgA)

• Baby immunisations take place after 3 months and before then get protection from mother

How to prevent pertussis before 3 months?

• Mother should be vaccinated with MMR as Rubella can severely damage foetus - 1 month before pregnancy

• Pregnant mothers have increased risk of death from Influenza

• NHS schedule offers these vaccines

• INFLUENZA + PERTUSSIS vaccine

Why is the MMR vaccine recommended before 1 month before pregnancy?

• Few cases of foetal abnormalities when pregnant mothers are vaccinated with MMR

• No proven direct link but guidelines suggest it 1 month before pregnancy and not during

What do vaccines induce?

• Active acquired immunity and immunological memory

• Immunological memory enables IS to recognise and respond rapidly to exposure

What should an effective vaccine trigger?

• Proliferation of naïve T cells

• Depends on whether Th1 and CTL responses are induced

• Otherwise, Th2 Ab responses are induced

• If you achieve both, that is best vaccine

What do memory cells do?

1. Naive T cells proliferate in response to antigen

2. Form effector cells

3. Also form memory cells which wait for infection as well as activating naive B cells

What are adjuvants and two groups of them?

• They enhance immunogenicity of protein antigens as they are poorly immunogenic when used alone in vaccine

1. Particulate vaccine delivery systems

2. Immunostimulatory adjuvants

How do particulate vaccine delivery systems work?

• Converts proteins to particles so they are more like bacteria/virus

• APCs preferably recognise and process particles

How do immunostimulatory adjuvants work?

Directly activate APCs through specific toll-like receptors resulting in inflammatory responses which amplify innate immune response

What are the principles of safe and effective vaccination?

1. Search for or create attenuated organisms with reduced pathogenicity to stimulate protective immunity

2. Inactivate organisms so they do not cause lethal systemic infections in immunosuppressed pts.

• Purified components of organism containing key antigens or nucleic acids which stimulate protective immunity are used now

8 requirements for an effective vaccination: PICODOSE

1. Depends on the organism

   • Intracellular organisms - CTL and Ab

   • Extracellular organisms - Ab

2. Provides defence at the point of entry

   • Stimulation of mucosal immunity may be required at specific mucosa

3. Pre-existing Ab may be required

4. Protection is optimised when specific epitopes are recognised

   • Immune responses are directed at multiple epitopes

   • Not all of these generate protective Ab or CTLs

   • Some may generate suppressor T cells

   • Therefore, correct epitopes must be targeted

5. Must be safe

   • SE reduce confidence in vaccines

6. Must protect most patients

   • Allows for rapid generation of herd immunity

   • Confidence

7. Must generate long-lived immunity

   • Booster immunisation is impractical

   • Cheaper and improves population health

8. Must be cheap

   • Will be administered to a large population

   • The benefit will be eroded if the cost per dose rises

What 3 categories impact the efficacy of a vaccine?

1. Features of vaccine itself

   • Immunogen design

   • Vaccine type

   • Formulation

   • Adjuvant

   • Dosing

2. Individual variations among recipients

3. Vaccine admin related factors

What do good vaccination schedules require?

• Require a minimal number of doses and an optimal interval between immunisations

• Complexity of vaccines types means no standard formula to determine appropriate vaccine strategy

Explain Parenteral Vaccination

• IM, SC or ID inoculation

• Relative immunogenicity of vaccines via these routes can vary depending on individual vaccines

• ID immunisation generates greater immune responses than IM

  • May be because the dermis contains more dendritic cells which facilitate the capture of antigens and local inflammation can induce maturation of the dendritic cells and their migration draining lymph nodes,

  • May be difficult to administer, particularly in children.

• SC and IM immunisation induce very similar responses in clinical studies

• There is less toxicity and anaphylaxis in IM (especially is using adjuvants) and easier to admin than ID or SC

How does oral/nasal dosing overcome many issues associated with IM?

• Less painful and expensive

• Immunologically, stimulates optimal immune response whilst IM does not due to pathogens route of entry

What are the social determinants of health that impacts all child health globally?

• Conditions of which people are born, grow, live, work and age

• Shaped by distribution of money, power and resources globally

• They are mostly responsible for health inequities

How is child health measured (mortality)?

• Neonatal mortality rate - number of baby deaths under 28 days old who die per 1000 live births in a given time period

• Infant mortality rate - Number of deaths in children under 1 year old per 1000 live births in a given time period

• Under 5 mortality rate - same as above for under 5s

How many strains of rotavirus is there and how common is it?

• 28 strains

• Common in infants under 5

Symptoms of Rotavirus and duration

• Severe watery diarrhoea

• Severe vomiting

• Fever

• Abdominal pain

• Loss of appetite

• Dehydration

• 3-8 days

How is it transmitted?

Faecal-oral transmission

What are the two vaccines available? Names
+ doses

1. Rotarix - 2 doses, 4 weeks apart before 24 weeks of age

2. Rotateq - 3 doses, 4 weeks apart before 26 weeks of age

• Live attenuated

What is Strep. pneumoniae?

• G+

• Droplet transmission

• Causes pneumonococcal pneumonia, meningitis, sepsis, otitis media and sinusitis

• Exacerbated by

  • Crowding

  • Indoor air pollution

  • Tobacco smoke

  • Immunosuppression

• Resistance to penicillin and other antibiotics

What is Haem. Influenzae?

• Small G- bacteria

• Type B is most virulent

• Transmitted via respiratory droplets

Steps that have to be in place for a child to get vaccinated?

• Parent knowledge of what’s required

• HP and human resources available

• Afford vaccine

• Transport to clinic

• Time to get to clinic

• Sterile equipment

• Parental consent

• Funding

• Infrastructure

• Government and leadership

• Regulation and research

• Legislation

Barriers to vaccines

• Vaccine beliefs

• Weak healthcare systems

• Increasing prices

• Pandemics make children miss out on basic vaccines

• Terrorism

• Fake immunisation programmes for military operations

Solutions to barriers to vaccines

• Healthcare system strengthening

• Education

• Ceasefires

• Peace

• Local manufacture of vaccines

• Improved monitoring

• Affordability

• Collaboration

What are some vaccine considerations?

• Biologically sourced materials include:

  • Bioactives

  • Bacterial polysaccharides

  • Proteins

  • Lipids

• Purity and virulence issues are paramount

• Unspecified trace contaminants

What do adjuvants do?

• Drug/immunological agent that modifies effects of other agents

• When added to vaccines they stimulate IS to respond to target antigen indirectly

• They often act as a depot for the antigen, presenting the antigen to the body over a longer duration than IV admin

• This maximises immune response

What are the 4 basic classes of adjuvants?

1. Water soluble/dispersible adjuvants

   • OM-174, soluble lipid derivative of E.coli - immunostimulant

2. O/W or W/O emulsion adjuvants

   • Mineral oil and snake venom peptide

   • Freund’s complete adjuvant - MPL - immunostimulant

   • Freund’s incomplete adjuvant

3. Entrapment of absorption agent adjuvants - particulate vaccine delivery system

   • Aluminium

   • Silica

   • Latex

   • Starch

   • Gelatine

4. Polymer particles and particulate adjuvants - particulate vaccine delivery system

   • Virosomes

   • Bacterial flagellin

   • Liposomes

Name 8 Formulation Stabilisers?

1. Freeze drying cryoprotectants

2. Buffers

3. Complexing and suspending agents

4. Relics

5. Delivery aids

6. Preservatives

7. Co-solvents

8. Emulsifiers

Why are antibiotic stabilisers used?

• Multi-use vaccines require special formulation as antibiotics prevent fungal and bacterial infection as consecutive aliquots are removed from same bulk container

• Process asepticity and hygiene - final product contain very low concentrations of antibiotics

What do chemical remnants often found in vaccines do?

• Remove pathogenicity and act as disinfectant for inactivated vaccines

  • Formaldehyde remnant is used to inactivate viruses via cross-linking with amine groups in nucleotides

Give examples of inactivators?

• Heat application

• Low pH-acid denaturation

• solvents and surfactants

• Irradiation

• Ethylene oxide

How are antigens purified?

1. Differential precipitation/solubilisation with ammonium sulphate and pH

2. Ultracentrifugation

3. Final purification

   • Ultrafiltration

   • Chromatography

4. Tested by ELIZA assay

What is the ELISA assay?

• Colour indicating popular microtitre plate-type assay of a solution which uses a solid phase immobilised enzyme in an immunoassay to detect presence of vaccine antigen

• Routine use for QC

Type of antigens in vaccines

• Homotypic - one type of component

• Heterotypic - Many types for various bacteria

  • Whole cell: live, killed etc.

  • Toxoid

  • Pathogen components

• Valency - Number of strains used

  • Bivalent

  • Quadrivalent

  • MMR has 3 organisms or singles

Types of QC

• Sterility - free of live microorganisms

• Chemistry standpoint: correct adjuvant, preservative where required and pH

• Content: uniformity of content and potency

• Safety: overdosing would carry no effective risk - correct labelling

• Efficacy: each antigen present meets regulatory requirements and satisfies key tests. No component interference

• Virulence testing: via passaging in suitable model

• Toxicity: no harm causing constituents

• Environment: no risk or harm of spread of dissemination

• Stability test: shelf life, optimal storage determination

• Chemical QC: moisture content, headspace vacuum, pH

2 dosage issues

• Variability: dose, response, maturity of IS

• Constancy: Formulation injection properties

What is the premise that effective vaccine delivery is based on?

• Efficient encapsulation of the active

• Successful targeting of the active to a specific region of the body and pathogen

• Successful release of the active in situ.

Principle routes of vaccine delivery?

1. IM

2. ID

3. SC

4. IN

5. Pulmonary

6. Oral

7. Topical

8. Biodegradable implant

9. Transdermal (needle free)

   • Patch

   • Liquid injection

   • Powder injection

   • Pre-filled reconstitution

10. Vaginal, cervical, anal, penile

4 steps to vaccine production

1. Growth

   • Virus grown on primary cells

   • Bacteria in bioreactors

   • Proteins or parts of the organism can be grown inside cells

2. Inactivation - heat and agents

3. Purification - filtration, chromatography

4. Formulation - Antigen + adjuvant + stabiliser + preservative

Sterilisation of vaccines

• Z - value defines temperature

• D - value defines number decrease at Z-value

• F0 - define total effective sterilisation time

• Sterilisation time/temp (e.g. 121º under pressured steam) for 6 minutes

QC and QA of vaccines

• Potency

• Safety

• Cost

• Preparation

• Usage

• Stability at 5ºC

• Cold chain conditions

Manufacturing Needs

• Safety reviewed by CHMP

• Staff bio-specific training

• cGMP

• Finished goods: PCQ

Storage of vaccines

• Cold chain has minimum and maximum

• Temp has effect on potency

• 3ºC storage in cold-chain

• Immunoglobulins can be stored at room temp for up to a week

• Vaccines sensitive to light, heat and freezing

Handling of vaccines

• Needs inventory management

• Emergencies procedure

• All attempts to reduce wastage which can account for up to 50% of all produced vaccines

• Most vaccines are damaged at freezing temps producing agglomerates and precipitates

• Data loggers and digital thermometers are needed

Antigenic evolution and new vaccinology

• Antigenic shift

• Antigenic drift and natural evolution

• Same strain, different virulence in new variant

• New exposure

• New transmission routes e.g. water to air

• Movement across the species

  • Avian - porcine - human

  • Ovine - bovine - human

  • Primate - simian - human

  • Canine - feline - human

• This was the basis of the worry with the global pandemic - evidenced by COVID

Manufacture Capability

• Ability to respond quickly to potential pandemic

• Respond to calls from health department

• Ability for biologicals manufacturers to collaborate (to effect mass manufacture)

• Cold chain and distribution systems to be effective

• Quarantine procedure if needed

Reasons for shortage of vaccines

1. Cold chain failures (e.g. HepB most susceptible to freezing damage)

2. Aggregation and degradation (poor storage)

3. Higher than normal demand

4. Production interruption

5. Lack of resources

   • US suffered a shortage of vaccines in last 15 years

   • Developing world even more marked. Due to mismanagement, trading corruption, natural disasters.

What is meningitis?

• Inflammation of meninges (A membrane enclosing the brain and spinal cord)

• Meningism refers to the signs and symptoms which accompany the inflammation

What pathogens can cause meningitis?

• Bacteria

• Viruses

• Fungal

• Protozoa

• Drug induced

Who is at risk of meningitis?

• Babies under 3 months old

• Immunocompromised

• Elderly

• Toddlers

• Young adults at uni due to close proximity and way disease spreads

• Sub-suharan Africa has increased risk

How are microbial agents of meningitis acquired?

• Droplet transmission

• Usually by organisms already in our biome which colonise back of the nose

  • Neisseria meningitis

  • Strep. pneumoniae

• Sometimes acquired from mother during birth

  • E.coli, group B streptococci

• Through food

  • E.coli, Listeria

• Airborne mucous transmission

What is viral meningitis?

• Most common form

• Not as severe as bacterial so cases go undetected

• Benign and doesn’t require medical attention

• Presents as flu-like illness

Symptoms of severe viral meningitis

• Nuchal rigidity

• Muscular pain

• N&V

• Diarrhoea

• Photophobia

• Requires hospital admission

Viruses implicated in viral meningitis

• Enteroviruses

• Mumps

• Herpes virus

• HIV

What is fungal meningitis caused by?

• Cryptococcus neoformans

  • Associated with immune deficiency

  • Symptoms appear more gradually, over days or weeks

    • Headache

    • Fever

    • N&V

    • Stiff neck

• Candida

• Coccidiodes immitis

• Histoplasma

• Requires antifungal treatment indefinitely

Explain bacterial meningitis

• Usually more serious than viral

• High fatality rate unless treated immediately

• Very quick progression of disease

• Even after antibiotic therapy, pts. are left with disorders

• Most common bacteria:

  • Strep pneumoniae

  • Neisseria meningitis

What is the progression to meningitis from nasopharyngeal colonisation?

1. Nasopharyngeal colonisation

2. Invasion of bloodstream or direct contact with meninges through head trauma

3. Bacteraemia

4. Meningeal invasion

5. Multiplication in subarachnoid space

6. Release of bacterial products and cytokines

Explain Neisseria meningitis

• Lives at back of throat but doesn’t mean you will get meningitis

• Type 4 pilus interact with CD46 receptor on host cell → Helps Neisseria transcytose across BB and get into subarachnoid

• G- organism have LPS presence and this can cause issues with temperature control resulting in high fever

Explain Streptococcus Pneumoniae

Produces pneumolysin as virulence factor

Why is it resistant to phagocytosis?

Most of these organisms are encapsulated making them resistant to phagocytosis

What is meningococcal septicaemia?

• Results when bacteria enters blood and multiplies uncontrollably

  • G- also release endotoxin which will activate IS and damage blood vessels making them leaky

  • Lower blood volume which is insufficient to carry O2 to all parts of body

  • This reduced blood flow to extremities = induces heavy breathing

• Blood leakage presents as non-blanching rash

• Clots may form in skin/muscle tissue which can result in amputation

Out of Men W, Y B and C which is most common cause?

B

What are other bacterial causes of meningitis?

• Strep pneumoniae (2nd biggest cause)

  • Produces pneumolysin which can cause lots of neurological damage

• Group A and B strep

• Type B haemophilus influenzae

• E.coli

• Listeria

• M. Tuberculosis

What are the early signs of meningitis?

• Fever

• Headache

• Vomiting

• Muscle pain

• Fever with cold hands and feet

• KEY: Rash NOT always present

What is the tumbler test?

• Someone who becomes ill rapidly should be carefully examined for meningococcal septicaemia rash

• Press glass tumbler against rash and if it doesn’t fade = possible infection

• On dark skin, check for rash on lighter areas of body like finger tips and feet soles

• Keep checking as rash may fade and come back

How quickly can meningitis kill?

4 hours

Diagnosis of Meningitis

• CSF may be taken, provided its not contraindicated

  • Visual inspection

  • Cell count is performed on an un-spun sample

  • Protein is analysed

  • Glucose levels are analysed

  • A centrifuged depot is gram stained and then inoculated onto range of media to support main pathogens

• These are usually done before antibiotics are given

• But may need to start on broad spec to be safe and then narrow down

Why may lumbar puncture be contraindicated?

Risk of herniation from increased inter-cranial pressure

Treatment of fungal meningitis

• Amphotecerin B

• Flucytosine

• Fluconazole

Treatment of viral

No specific unless HSV - Aciclovir

Treatment of bacterial

• Transfer to hospital

• If meningococcal is suspected, benzylpenicillin given prior to hospital transfer

  • Want to prevent endotoxins spreading

• Consider adjuntive treatment with dexamethasone - shown to reduce neurological SE but not appropriate in all pts.

Life after meningitis bacteria vs viral

• Viral - barely any long-term issues

• Bacterial:

  • May fully recover if treated early enough

  • Can result in long term issues like:

    • Hearing or vision loss

    • Memory or epilepsy

    • Co-ordination, movement and balance issues

    • Loss of limbs