Vaccines Flashcards
What is a vaccine?
Something that stimulates the immune system, without causing serious harm or side effects
How can vaccines be administered?
- Injection
- Nasal spray
What are the 7 considerations made when making a vaccine?
- Safety
- Easy to administer
- Cheap
- Stable
- Active against all variants
- Provides life-long protection
How do vaccines work?
Trains immune system to recognise and remember an infection without actually infecting the patient
Are vaccines effective?
Yes - very —> eradicated smallpox
What are the ways vaccines can stimulate a better secondary immune response?
- Stimulate prevention of entry
- Antibodies and macrophages - Stimulate kill of infected cells
- CD8 T cells - Boost overall immune response
- B cells and CD4 T cells
What is the overall aim of vaccines?
Reduce community spread of an infection
What is R0?
Basic reproductive number
- Number of cases one case generates on average
What do vaccines aim to do to R0?
R0<1
—-> Over time, number of cases decrease
What is herd immunity?
Indirect community immunity when most are immune
How do vaccines achieve herd immunity?
Decrease chance infected person interacting with susceptible (unvaccinated) host and transmitting infection
What are the 5 components of a vaccine serum?
- Water
- Active ingredient
- Adjuvants
- Residual traces
- Preservatives and stabilisers
What is the function of water in vaccines?
Main ingredient containing all other components
What is the function of the active ingredient in vaccines?
Specific pathogen that will stimulate primary immune response
What is the function of adjuvants in vaccines?
Boost immune system
What is the function of preservatives and stabilisers in vaccines?
Maintain vaccine quality and safety (prevent contamination)
Why do you get residual traces in a vaccine?
Part of vaccine manufacturing process
What are the 4 types of vaccines?
- Inactivated toxoid
- Conjugate
- Dead pathogen
- Live attenuated
What are inactivated toxoid vaccines?
Vaccines containing chemically inactivated form of pathogen toxin
What is an example of an inactivated toxoid vaccine?
Tetanus toxoid
- Stimulates antibody production —> blocks toxin binding nerves
What are the pros and cons of inactivated toxoid vaccines?
Pros:
- Cheaper
- Safe
- Been used for decades —> lots of research
Cons:
- Only works for pathogens encoding toxins
- Need good understanding of infection biology
What are recombinant protein vaccines?
vaccine containing recombinant protein from pathogen (eg. surface antigen)
What is an example of a recombinant protein vaccine and how does it work?
HbSAg (HeP B surface antigen)
- Stimulates neutralising antibody production
What are the pros and cons of recombinant protein vaccines?
Pros:
- Pure
- Safe
Cons:
- Expensive
- Not very immunogenic (ability to stimulate immune response)
- Doesn’t work against capsulated bacteria
What type of pathogen do recombinant protein vaccines not work on and why?
Capsulated bacteria
- Polysaccharide capsule hides antigens
What are conjugate vaccines?
Vaccine containing a combination of a weak antigen with a strong antigen as a carrier
What is an example of a conjugate vaccine and how does it work?
S. pneumoniae
- Polysaccharide coat component conjugated to immunogenic carrier protein
- Stimulates Th cells to activate B cells against polysaccharide
What are the pros and cons of conjugate vaccines?
Pros:
- Improves vaccine immunogenicity
- Highly effective against bacteria
Cons:
- Expensive
- Susceptible to carrier protein interference
- Very strain specific
How do conjugate vaccines make T-independant B cells T-dependant?
- BCRs bind to polysaccharide part
TCR binds to carrier protein part - Stimulates cognate T cell/B cell interaction
- Enhances production of anti-polysaccharide antibodies
What are dead pathogen vaccines?
Vaccines containing a chemically pathogen
What is an example of a dead pathogen vaccine and how does it work?
Influenza split vaccine
What are the pros and cons of dead pathogen vaccines?
Pros:
- Immunogenic
- Cheap
- Quick
Cons:
- Killing of bacteria alter chemical structure of antigen
- Need to grow pathogen
- Risk vaccine-induced pathogenicity
- Risk contamination with live pathogen
What are live attenuated vaccines?
Vaccine containing live but weakened pathogen
What are 3 examples of a live attenuated vaccine and how does it work?
- BCG
- LAIV
- OPV
- Attenuate pathogen via serial passage —> lose virulence factors
- Pathogens still replicate —> triggers innate immune response
What are the pros and cons of live attenuated vaccines?
Pros:
- Strong immune response
- Response may be localised (LAIV)
Cons:
- Pathogens can revert to being active
- Vaccine may infect immunocompromised
- Other infection may outcompete pathogen from virus
What are adjuvants?
Substances added to vaccines to produce a more robust immune response
How do adjuvants boost the immune system?
Induce signals that activate dendritic cells to present antigen to T cells in lymph nodes
What are 2 examples of adjuvants?
- AS03 —> chicken pox, malaria (+ potentially Tb, COVID-19)
- MF59 —> influenza
What are the 5 reasons for new vaccine production?
- Demographics changing - aging in UK
- Environments changing - global warming —> pathogens found in new locations
- New diseases - eg. COVID-19
- Old diseases without vaccines present - eg. HIV/TB
- Antibiotic resistance - new approach to bacterial infection control
What are the 5 barriers to vaccine production?
- Scientific challenges
- Injection safety
- Logistics of cold chain (transporting, storing, and managing)
- Development time and cost
- Public expectation - want risk-free vaccines
How long to vaccines take to produce?
15 years
What are 3 examples of viruses that need vaccines targeting multiple strains?
- HIV
- Influenza
- Rhinovirus
Which … infections are attenuated vaccines used against?
Bacterial:
1. Chicken pox
2. Cholera
3. Anthrax
4. Typhoid
5. TB (BCG)
Viral:
1. Rabies
2. Yellow fever
3. Influenza
4. Polio
5. Measles
6. Mumps
Which 4 infections are inactivated toxoid vaccines used against?
Bacterial:
1. Diptehria
2. Tetanus
3. Typhus
4. Whooping cough
Which 2 infections are conjugation vaccines used against?
Bacterial:
- Pneumococcus —> pneumonia
- Meningococcus —> meningitis
Which 3 pathogens are recombination vaccines used against?
Viral:
1. Hep A
2. Hep B
3. HPV
Which 3 infections are vaccines being developed for?
- COVID-19
- Malaria
- Dengue
What are the 8 options for SAR-CoV-2 vaccine active ingredients?
- Live attenuated virus particles
- Live recombinant viral vector
- VLPs
- Inactivated virus particles
- Proteins
- mRNA
- saRNA
- DNA
What are the 6 phases of vaccine approval?
- Pre-clinical tests
- Phase 1 —> 20-80 humans
- Phase 2 —> 100-300
- Phase 3 —> 1,000-3,000
- FDA review
- Phase 4 —> 1,000 participants
When are drugs approved for testing in humans?
After pre-clinical testing
When are drugs approved for use?
After FDA review
When are drugs submitted for FDA approval?
After Phase 3
How did SAR-CoV-2 vaccines get released so quickly?
Large-scale production started in phase 2 and 3
Which 6 organisations need to approve vaccines in the UK?
- MHRA —> licensing
- JCVI —> recommendations
- DH —> decide vaccine policies
- Pharmaceutical company —> sells vaccine to DH
- NIBSC —> control vaccine distribution and use
- UKHSA —> post-licensure assessment
What are the 8 considerations when making a vaccine schedule?
- Aim
- Need for vaccine (prevalence of infection)
- Scheduling with other vaccines
- Availability
- Cost
- Accessibility by population
- Cultural attitudes and practises towards vaccines
- Delivery facilities
What are the 4 age stages of the baby vaccination schedule?
- 8 weeks old
- 12 weeks old
- 16 weeks old
- 1 year old
Which 3 vaccines are given at 8 weeks?
- DTaP/IPV/HiB/HepB (Infanrix hexa)
- MenB
- Rotavirus
Which 3 vaccines are given at 12 weeks?
- DTaP/IPV/HiB/HepB (Infanrix hexa)
- PCV
- Rotavirus
Which 2 vaccines are given at 16 weeks?
- DTaP/IPV/HiB/HepB (Infanrix hexa)
- MenB
Which 4 vaccines are given at 1-year?
- Hib/MenC
- PCV booster
- MMR
- MenB booster
