3.1.7 Vaccination

• How does vaccination make a person immune to a disease?

  1. Small quantities of dead / inactive forms of a pathogen introduced into body

  2. Antigen (on surface of pathogen) stimulates WBCs to produce unique antibodies

  3. Memory cells (a type of WBC) remain in body

  4. If same pathogen (with same antigen) re-enters the body, memory cells respond quickly to produce the correct antibodies in larger quantities

  5. So pathogens are destroyed / killed before numbers are high enough to cause disease
• How can vaccination reduce spread of a pathogen?

  ● Vaccinate a large proportion of the population

  ● So a large proportion of population are immune and therefore do not become ill from infection

  ● So fewer infected people to pass pathogen on / unvaccinated people less likely to come in contact with someone with disease
• why is this statement wrong?

  “A vaccination contains a dead / inactive form of a disease.”

  A vaccination contains a dead / inactive form of a pathogen. A pathogen is a microorganism that causes disease.
• why is this statement wrong?

  “Once antibodies have been produced they wait around for future invading pathogens.”

  Antibodies produced don’t remain in the blood forever; they break down. It is the memory cells that ‘wait around’ and are able to quickly produce the correct antibody if the same pathogen re-enters the body
• why is this statement wrong?

  “The body remembers the pathogen.”

  This is too vague. It is the memory cells that recognise the pathogen and are able to quickly produce the correct antibody.
• why is this statement wrong?

  “Being vaccinated means you cannot catch the pathogen.”

  You can still catch the pathogen but it should not lead to disease / becoming ill due to the rapid production of antibodies. These help destroy the pathogens before their numbers get high enough to cause disease.
• Vaccination against measles will not protect a person against HIV. Explain why. (1)

  ● Antibodies are specific / needs different antibodies (as have different antigens)
• The government needs to decide whether to make the chickenpox vaccination free to all children. Suggest two factors the government should consider when making this decision. (2)

  ● Cost to the NHS

  ● Money saved through not treating people with chickenpox

  ● How effective the vaccine is

  ● Severity of the disease
• Suggest how a vaccine against malaria could reduce the spread of the disease. (2)

  ● Vaccine would make people immune

  ● So fewer infected people to pass pathogen on (to mosquitos)
• Suggest how a vaccination programme would reduce the number of people with TB. (2)

  ● Provides immunity / protection to TB

  ● Prevents TB spreading