Lecture 6: Vaccination Flashcards
what is vaccination/immunization?
Controlled exposure to a vaccine to produce immunity against the disease to prevent/reduce mortality and morbidity while promoting protective memory immune responses
Do we vaccinate for every disease?
No, only diseases that have high mortality/morbidity
what is the first misconception of vaccination?
Natural exposure is better. This is not true!
What is immunological memory?
The ability of the acquired immune system to respond more rapidly and effectively to pathogens that have been encountered before.
explain what this diagram shows and how vaccination is involved
When encountered by a primary infection, it takes round 7 days for the acquired immune system to get going. Sometimes, the infections work very quickly in these 7 days and bad things could happen to you, including death. If you survive these 7 days, the antibody and effector T cells will get rid of the infection and you start to get better. When you encounter a secondary infection, the T and B cells respond faster and the immune response is way bigger and better, so the infection should only be mild.
Vaccines intend to replace the primary infection so the memory cells are there for the next time you are exposed
What are the 2 types of memory cells?
T cells and B cells
What are the feature of B cells?
- make IgG rather than IgM (isotype switching)
- high affinity Ig (affinity maturation)
- high precursor frquency (clonal expansion)
- already express activation molecules
What are the feature of T cells?
- high precursor frequency
- already differentiated (Th1, Th2)
- already express activation molecules
- high affinity T cell receptor
what affect do memory T and B cells have on infection?
the infection does not occur, is sub-clinical or mild
Does only ‘living and eating healthily’ outweigh the need for vaccines?
No. this is another misconception.
what do we need for immunisation success?
- Safe and effective vaccines
- high uptake of completed immunisations
Are vaccines safe? what about the bad reactions to it?
- vaccines are safe
- more benefits than risks
- some vaccines have serious reactions, but these are rare and must be weighed against the protective benefits of vaccines.
does sanitation work better than vaccines?
No, it helps decrease disease but it not the only answer.
What are some practical considerations of a high uptake of vaccinations?
- cost: few cents to hundreds of dollars
- logistics: how, where, who (equity), stability?
- ease of administration: injection vs oral
the impact of these depends on a target group like health professionals or all children etc.
why are vaccines important even if the majority of people who get diseases are vaccinated?
This is another misunderstanding. Vaccines work at an individual and community (herd) level. If more people are vaccinated, then of course more people will be diseased as being vaccinated doesn’t mean you won’t get the disease. However, by having the majority of a population vaccinated, it allows for herd imminity to take place and protect people who are too young or too old to be vaccinated.
What is R0?
Basic reproduction number.
- how many people will you infect if you are infected.
explain the herd immunity threshold?
this is the percentage of people in a population that should be immune to the disease in a population (either through vaccination or having the disease before) in order to reduce the spread of the disease.
Which vaccines are given during pregnancy according to NZ immunisaiton schedule?
- Boostrix - Tdap
- Influvac Tetra - Influenza
Which vaccines are given at 6 weeks according to NZ immunisaiton schedule?
- Infanrix-hexa - DTaP - IPV - HepB/Hib
- Synflorix - PCV10
- Rotarix - RV1
Which vaccines are given at 3 months according to NZ immunisaiton schedule?
- Infanrix-hexa - DTaP - IPV - HepB/Hib
- Rotarix - RV1
Which vaccines are given at 5 months according to NZ immunisaiton schedule?
- Infanrix-hexa - DTap-IPV-HepB/Hib
- Synflorix - PCV10
