12 - vaccination Flashcards
How do vaccines work?
They induce immunity and immulogical memlry which allows rapid recognition and response to disease, which prevents or reduces the risk of disease and it’s effects
What is the difference between vaccination and immunisation?
- Vaccination is the administration of antigens (in a vaccine) into the body
- Immunisation is the process by which you develop immunity against a disease, as a result of being vaccinated
What are the requirements of a good vaccine?
- they elicit a response that gives the same immune protection that usually follows from natural infect without causing disease
- safe (no side effects or contraindications)
- stabile (doesn’t need to be kept cold)
- relatively cheap
- easily administered
- provides long term protection
- interrupts spread of infection
What are the three main types of vaccine?
Live vaccines
- inactivated vaccines
- subunit vaccines (including toxoid, surface protein, viral vector and RNA/DNA vaccines)
What is a live attenuated vaccine?
A whole pathogen that has artificially reduced virulence (e.g. through mutation)
What are some advantages of live attenuated vaccines?
- inexpensive and easily administered (can be supplied as an oral dose)
- induces both mucosal and systematic immunity
- short term shedding of the vaccine in faeces can result in passive immunisation of people in close contact
- life long immunity
What are the disadvantages of live attenuated vaccines?
- May induce mild symptoms of the disease
- can’t be given to immune compromised or pregnant patients
- unstable (only lasts 6 weeks at room temperature)
- May revert to virulent form and cause disease (particularly in types 2 and 3 Polio)
What are the disadvantages of the inactivated polio vaccine compared to the live attenuated polio vaccine?
- the inactivated vaccine is more expensive and has to be administered via infection
- the inactivated vaccine does not provide mucosal immunity which means that the individual is protected, but the wild virus can still multiply in the gut and be transmitted to others
What are the advantages of inactive vaccines?
- can’t cause infection
- can be given to immunosuppressed and pregnant patients
What are the disadvantages of inactive vaccines?
- less immunogenic and require the addition of adjuvants and booster doses
- usually have to be administered via injection
What does an adjuvant do?
enhances immune response by slowing the release of the vaccine and provoking a local inflammatory response
What is a toxoid vaccine and how does it work?
A vaccine that uses a detoxified version of the toxins produced by bacteria. The adjusted toxins have the same antigenicity, which allows the body to neutralise the toxin so that the immune system can remember how to do this when infected, therefore preventing disease.
How were surface protein vaccines originally made?
The surface coat protein was purified from the blood of carriers and then inactivated.
What are the disadvantages of the original method of producing surface protein vaccines?
- they were derived from human blood so there was a risk of viral transmission
- extremely expensive to produce
How is the hepatitis B surface protein vaccine made now?
The gene in coding for the surface protein (HbsAg) has been cloned and is expressed in either yeast or Chinese hamster ovary cell then purified
