Immunity And Vaccines - Tutorial 3
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Name the four different types of vaccines
• Live attenuated microbes • Killed whole microbes • Portions of microbes • Toxoids
Name the four types of acquired immunity & describe how immunity is achieved for each type
Naturally acquired: * Active - natural exposure to the antigen (e.g viruses, cuts, etc) * Passive - antibodies passed to foetus via placenta or to infant via breast milk Artificially acquired: * Active - antigens introduced via vaccines - body makes antibodies and memory cells * Passive - preformed antibodies injected (e.g tetanus, Hep B)
Identify which type of vaccine would give the most effective response and explain why
Live attenuated vaccines, often provide life -long immunity, without the need for boosters, thus are more effective than other vaccines
Explain why a booster vaccine might be needed
• When a vaccine involves killed whole bacterial cells, toxoids, inactivated microbes or sub-units the immune system does not respond as powerfully as when a live attenuated vaccine is given • Boosters are needed to intensify the immune response.
Describe the concept of herd immunity
Herd immunity results when most of a population is immune to a disease, if most people are immune they will not be carriers, so herd immunity protects those who are immune
List the undesirable responses of the immune system
• Hypersensitivity reaction: - Allergy is a hypersensitivity to an environment antigen. - Anaphylaxis is the most severe and rapid reaction. It is life-threatening as it causes construction of the bronchial smooth muscle and oedema of the throat • Autoimmune disorder: - The immune system attacks the body’s own cells when it fails to recognise ‘self’ eg. Rheumatoid arthritis • Immuno-compromised persons are at risk from minor infections - Very young, elderly, severe illness, stress • Reactions to transplanted or foreign tissue including blood transfusion reactions, donated organs, etc • Chronic inflammation - Asthma is a disorder characterised by chronic airways inflammation (as well as hypersensitivity to a variety of stimuli). Inhalers which act as preventers reduce inflammation. Chronic inflammation of arteries plays a key role u the development of atherosclerotic plaque in response to damage to the endothelial lining of the artery (through smoking, high BP, high BGL)