Lecture 6: Vaccines Flashcards
Types of vaccines:
- Live (attenuated) vaccines
- contain attenuated replicating strains of pathogen
- strong enough to cause immune response, but too weak to cause significant
disease manifestations - Non-live (‘inactivated’) vaccines
- contain antigenic components of a pathogen (subunit or toxoid) or killed whole
organism
- often combined with an adjuvant to improve their ability to induce an immune
response - Other
- viral vectors, nucleic acid-based RNA and DNA vaccines, virus-like particles
Types of Live and non-live vaccines and examples of diseases prevented by them
- Live attenuated
Mealses, mumps,rubella, yellow fever, influenza, typhoid - Killed whole organism
Whole cell whooping cough, influenza, Hep A, rabies - Toxoid
Tetanus - Subunit
Whooping cough, influenza, Hep A and B, typhoid
Types of other vaccines and example diseases prevented
- Virus like particle
Human papillomavirus - Outer membrane vesicle
Group B meningococcal - Protein-polysaccharide conjugate
meningococcal, pneumococcal, typhoid - Viral vectored
Ebola - Nucleic acid
SARS-CoV-2
What is a combination vaccine and why have it?
Combination vaccines take two or more vaccines that could be given individually and put them into one shot
Why?
- Reduces trauma for parent and child
- Higher rates of compliance
- Increased vaccine coverage
Vaccine schedule:
6 weeks:
Rotarix (oral), synflorix, infranix hexa
3 months:
Rotarix, infranix hexa
5 months: Synflorix, infranix hexa
12 months: Synflorix, priorix
15 months: priorix, varivax, hiberix
Components of a vaccine
Stabilisers
Emulsifiers
Preservatives
Trace elements e.g. antibiotics, egg or yeast proteins, latex, formaldehyde, acidity regulators
May cause allergic reaction but other than this does not pose a risk to human health or cause autism.
Route of administration and examples
Intramuscular (IM) injection - administered into the muscle mass. - vaccines containing adjuvants should be injected IM to reduce adverse local effects. -Hep A
Subcutaneous (SC) injection
- administered into the subcutaneous layer above the muscle and below the skin.
- MMR
Intradermal Injection
- just below the external skin layer
- Hep B
Oral route
- Drops in the mouth
- Rotavirus vaccine
Intranasal Route
- administered into each nostril using a
nasal sprayer
- live, attenuated influenza vaccine
Vaccine sites for age groups
- Infants 0 months to 12 months – thigh
- Young child 12 months to 3 years - thigh or arm
- Older child 3 years and over - arm
Common and rare side effects of vaccines
Common side effects:
- injection site pain, redness and swelling
- systemic symptoms such as fever, malaise and headache.
- occur in the first 1–2 days following vaccination (reflecting the inflammatory and immune responses)
Serious side effects:
Anaphylaxis
Contradictions for vaccines
Immunodeficiency and vaccination
- Most vaccines are safe, live vaccines are generally avoided.
- Induction of immunity may not be possible, depending on the nature of the immune system defect.
- In individuals with antibody deficiency, there may be some merit in the use of routine live vaccines, as T cell memory may be induced that, although unlikely to prevent future infection, could improve control of the disease if infection occurs.
Allergy and vaccination
- People with known allergies to possible vaccine trace components (such as egg or latex) should avoid vaccines that may have these traces.
How are vaccines developed
Research and development
- Identify antigens
- same or mutating?
- Decide vaccine platform
- live attenuated, subunit, etc - How will it be administered?
- injection, oral, nasal
Initial Testing (Pre-clinical Trials) - subcultures, animal models, etc
GMP certification
- can it be manufactured to high standard and scale?
Human Trials
- 3 Phases, all have to be passed
Human Trial phases
Phase 1 – Safety Trial
- Given to small group of healthy people to
look for adverse reactions
Phase 2
- Work out dose required to give maximum
immune response
- Given to 100s of people
Phase 3
- World-wide study
- Given to 1000s of people to see how effective vaccine is.
- Slowest - Can take decades!
Licensed for use
Phase 4 – monitoring
- Keep track of rare adverse reactions
Immunisation principles: Active vs passive immunity
Active immunity Individuals’ immune system stimulated to produces antibodies - Natural – infection - artifical – immunisation - Not immediate, takes time - Long-lasting immunity
Passive immunity
Individual given antibodies
- Natural – transfer of antibodies from mother to foetus/infant through placenta/breastmilk
- artifical – infusion of blood products,
immune globulin eg tetanus, Hep B - Immediate
- Temporary, wanes over time (weeks/months)
Vaccine immunisation principle (innate and adaptive process using adjuvant vaccine)
Lecture slide diagram
Vaccine doesnt have PAMPs (purified) and therefore adjuvants act as PAMPS
Conjugate vaccine principle and effects
Polysaccharide vaccines induce antibody- producing plasma cells by cross-linking the BCR.
- no memory B cells
- no immune response in infants under 2
- short lived antibody production
- No affinity maturation
Protein–polysaccharide conjugate vaccines can engage Th cells that recognise the carrier protein, as well as B cells that recognize the polysaccharide.
- memory B cells made
- immune response in infants under 2
- long lived antibody production
- affinity maturation
