Vaccines

• What is a vaccine?

  A suspension of antigens that are intentionally put into the body.
• What does vaccinations induce?

  Artificial active immunity
• What are the two main types of vaccines?

  Live attenuated and inactivated
• where are vaccines injected?

  into a vein or muscle
• How do vaccinations produce long-term immunity ?

  they cause memory cells to be created The immune system remembers the antigen when reencountered and produces antibodies to it, in what is a faster, stronger secondary response.
• How effective are vaccines?

  Highly effective with one vaccination giving a lifetime’s protection. Generally harmless as they do not cause the disease they protect against because the pathogen is killed by the primary immune response
• What problems may occur with vaccinations?

  People can have a poor response (e.g. they are malnourished and cannot produce the antibodies – proteins or their immune system may be defective)
• What is antigenic variation and what effect does it have on vaccination?


  the variation in the antigens of pathogens causes the vaccines to not trigger an immune response or diseases caused by eukaryotes (e.g. malaria) have too many antigens on their cell surface membranes making it difficult to produce vaccines that would prompt the immune system quickly enough
• What is antigenic concealment and what effect does it have on vaccination?

  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 (e.g. Vibrio cholerae – cholera, remains in the small intestine)
• Who discovered the principles underpinning vaccines?

  Edward Jenner in the 1700s
• What are live attenuated vaccines?

  They contain whole pathogens that have been 'weakened'.
• How do attenuated vaccines work?

  Weakened pathogens multiply slowly allowing body to recognise antigens and trigger primary response. E.g. MMR
• What are inactivated vaccines?

  They contain whole pathogens that have been killed or small parts of the pathogens.
• What are the pros and cons of inactivated vaccines?

  As they don't contain living pathogens they cannot cause disease even for those with weak immune systems.

  However they don't trigger a strong or long-lasting immune response so repeated doses and or booster doses are often required.
• Name an example of a whole killed vaccine.

  The polio vaccine
• Name an example of a toxoid subunit vaccine,

  Diptheria
• What is herd immunity?

  When a sufficiently large proportion of the population has been vaccinated which makes it difficult for a pathogen to spread within that population

  Those who are not immunised are protected and unlikely to contract it as the levels of the disease are so low.
• Why is herd immunity important?

  It allows for the individuals who are unable to be vaccinated (e.g. children and those with weak immune systems) to be protected from the disease.
• What happens if vaccination rates fall below the required level?

  herd immunity can break down