Topic 2- Vaccines Flashcards
Define vaccine
a suspension of antigens that are intentionally put into the body to induce artificial active immunity. A specific immune response where antibodies are released by plasma cells
What are the two types of vaccines
-Live attenuated
-Inactivated
How are vaccines administered?
-By injection (into vein or muscle)
-Orally
What do vaccines produce?
-Long term immunity as memory cells are produced
Give 2 advantages of vaccines
-Highly effective vaccines will last a lifetime (less effective ones will require a booster)
-Generally harmless
What are 3 disadvantages of vaccines
-Can have a poor response
-Antigenic variation-he variation (due to major changes) in the antigens of pathogens causes the vaccines to not trigger an immune response or diseases caused by eukaryotes (eg. malaria) have too many antigens on their cell surface membranes making it difficult to produce vaccines that would prompt the immune system quickly enough
-Antigenic concealment – this occurs when the pathogen ‘hides’ from the immune system by living inside cells or when the pathogen coats their bodies in host proteins or by parasitising immune cells such as macrophages and T cells (eg. HIV) or by remaining in parts of the body that are difficult for vaccines to reach
What do live attenuated vaccines contain?
-Whole pathogens which have been weakend
How do live attenuated vaccines work?
-weakened pathogens multiply slowly allowing for the body to recognise the antigens and trigger the primary immune response (plasma cells to produce antibodies)
Who are live attenuated vaccines unsuitable for?
people with weak immune systems as the pathogen may divide before sufficient antibodies can be produced
What do inactivated vaccines contain?
Whole pathogens that have been killed
Why are inactivated vaccines suitable for those ith poor immune systems
They do not contain living pathogens so they can’t cause disease
Why are Repeated doses and/or booster doses are often required for inactivated vaccines
do not trigger a strong or long-lasting immune response like live attenuated vaccines
Why do some people have allergic reactions or local reactions to inactivated vaccines?
adjuvants (a substance which enhances the immune response to an antigen) may be conjugated (joined) to the subunit of the pathogen to strengthen and lengthen the immune response
Define herd immunity
when a sufficiently large proportion of the population has been vaccinated (and are therefore immune) which makes it difficult for a pathogen to spread within that population
Why is herd immunity important?
allows for individuals who are unable to be vaccinated (e.g. children and those with weak immune systems) to be protected from the disease
