Immunisation Flashcards
When did principles of immunisation first established?
Date back to the ‘nineteenth century’
When Edward Jenner published the 1st description of vaccination against small pox
Negative example in the history of immunisation/vaccination
In 1906,
A cholera vaccine study accidentally muddled “vaccine serum” with “bubonic plague serum” >>> infected and killed 13 participants
(But we should NOT dwell on that, immunisation has immeasurable benefits to society & to eradication of many diseases)
Positive example in the history of immunisation/vaccination
Near eradication of polio in the world
More than 60 thousands in 1980 to in few hundreds cases in 2004 in the whole world
How can immunisation against a specific pathogen be generated artificially?
Either actively or passively
Principles of passive immunisation
Administration of pre-formed antibodies against a particular antigen
Passive immunisation: Examples
(Preformed antibodies: Examples)
- Tetanus
- Varicella
- Rabies
- Hepatitis B
- Botulism
- Diphtheria
Passive immunisation: advantage
It provides instantaneous immunity within 24 to 48hours
Passive immunisation: Time of use
Immediate post-exposure prophylaxis
Why is passive immunisation (pre-formed antibody) given as immediate ‘post-exposure prophylaxis’?
Because it provides instantaneous immunity within 24 to 48hours
Passive immunisation: disadvantges
- Immunity only lasts for the half-life of the immunoglobulin (30days)
- As it is a blood derived product >>> risk of TTIs (Transfusion transmitted infections)
Principles of active immunisation
To expose the ‘adaptive immune system’ to a stimulus (virus, bacteria, toxin) >>> to generate a lasting response
Different methods of active immunisation/vaccination
(Different types of vaccines)
- Live vaccines
- Killed vaccines
- Subunit vaccines
Killed and subunit vaccines are more common than live vaccines
Live vaccine: Examples
- Yellow fever
- MMR (Measles-Mumps-Rubella)
- BCG (Bacille Calmette Guerin)
- Varicella (Also has pre-formed antibodies)
- Oral Polio (No longer available in the UK)
Killed vaccines (=Killed whole organism): Examples
- Seasonal flu (Annual flu jab)
- Typhoid
- Rabies (Also has pre-formed antibodies)
- Pertusis
- Cholera
- Parenteral polio
Subunit vaccines (= Subunits of organism): Examples
- Pneumococcus (Pneumococcus polysaccaride vaccine: PPV or PPSV)
- Hib (Haemophilus influenzae type B)
- Hepatitis B
- Meningococcus
- HPV (Human papilloma virus)
Why do we use live vaccines (containing live organisms)?
Some antigens are inherently less immunogenic
Live vaccine: contraindications
Immunodeficiency (primary or secondary)
Conjugate vaccine: Examples
Prevener: Conjugate pneumococcal vaccine
(Conjugated polysaccaride vaccine with a protein)
Polysaccaride vaccine is conjugated with what?
A protein
Conjugate vaccine: advantages
Conjugation stimulates a cellular response >>> improves likelihood of protective immunity
Are vaccination/immunisations 100% protective/effective?
NO
No vaccine is 100% effective
If immunisations are NOT 100% effective, upon which do they rely on?
On the principles of “herd immunity”
Concept of herd immunity
It relies on the premise that >>>
- For infections to gain ground in a population >>> they need to spread in chain from one person to the next
- If a significant proportion of the population has reduced susceptibility >>>>> these chain fails to develop >>>>> infection rates diminish in both vaccinated and unvaccinated individuals
