5.6 - Vaccination

Question 1

What are the 2 types of immunity

Answer 1

• Active immunity
• Passive immunity
  —> both can be artificial or natural

Question 2

What is passive immunity + example

Answer 2

• produced by the introduction of antibodies into individuals from an outside source
• No direct contact with the pathogen or its antigen is necessary to induce immunity
• immunity is acquired immediately
• As the antibodies aren’t being produced by the individual = they cannot be replaced when they’re broken down because no memory cells are produced. Hence why passive immunity gives no long lasting immunity
• NATURAL PASSIVE IMMUNITY EXAMPLE: Antibodies received from mother via breast milk or placenta
• ARTIFICIAL PASSIVE IMMUNITY EXAMPLE: injection of antiserum containing antibodies, e.g. anti-venom

Question 3

What is Active immunity + examples

Answer 3

• is produced by stimulating the production of antibodies by the individuals’ own immune system.
• Direct contact with the pathogen or its antigen is necessary
• immunity takes time to develop, but is long-lasting
• NATURAL ACTIVE IMMUNITY EXAMPLE: Being infected and recovering from a pathogen
• ARTIFICIAL ACTIVE IMMUNITY EXAMPLE: vaccination = antigens are received in a jab

Question 4

What is a vaccination

Answer 4

• The introduction of the appropriate disease antigens into the body, either by injection or by mouth
• The intention is to stimulate an immune response against a particular disease
• The material introduced is called vaccine, may contain 1 or more types of antigens from the pathogen
• these antigens then stimulate an immune response

Question 5

Describe the immune response that a vaccine stimulates

Answer 5

• very small = only a small amount of pathogen has been introduced
• the crucial factor is that memory cells are produced
• these remain in the blood and allow a greater, and more immediate response to a future infection with the pathogen
• the result is that there’s a rapid production of antibodies and the new infection is rapidly overcome before it can cause any harm and with few, if any symptoms

Question 6

What are the 3 main types of vaccines

Answer 6

• Inactivated
• live attenuated
• Toxoid

Question 7

Describe how vaccines work (5 marks)

Answer 7

1. Vaccines contain antigens and are injected
2. Body fights dead pathogens/weakened pathogens
3. Memory cells are made
4. On 2nd exposure memory cells produce antibodies/become active
5. Rapidly producing antibodies in high quantities, lasting longer
6. Antibodies destroy pathogens
7. Leads to herd effect as fewer people pass on the disease

Question 8

What is the key things to remember about a secondary response

Answer 8

• antibodies are created quicker
• antibodies are created in higher quantities
• last longer

Question 9

What are some of the factors that a successful vaccination programme depends on

Answer 9

• A suitable vaccine must be economically available in sufficient quantities to immunise most of the vulnerable population
• there must be as little as possible side-effects. Unpleasant side-effects may discourage individuals in the population from being vaccinated
• means of producing, storing and transporting the vaccine must be available. This usually involves technologically advanced equipment, hygienic conditions and refrigerated transport
• there must be the means of administering the vaccine properly at the appropriate time. this involves training staff with appropriate skills at different centres throughout the population
• It must be possible to vaccinate the vast majority of the vulnerable population in order to produce herd immunity

Question 10

What is herd immunity

Answer 10

• It arises when a sufficiently large proportion of the population has been vaccinated to make it difficult for a pathogen to spread within that population

Question 11

Why is herd immunity important

Answer 11

• its never possible to vaccinate everyone in a large population, e.g. babies (because their immune system isn’t fully developed)
• it can also be dangerous to vaccinate those who are ill or have a compromised immune system

Question 12

Why may vaccination not eliminate a disease

Answer 12

• it fails to induce immunity in certain individuals, e.g. people with defective immune systems
• individuals may develop the disease immediately after vaccination before their immunity levels are high enough to prevent it
• pathogen may mutate = antigens change suddenly rather than gradually = vaccines become ineffective because immune system can’t recognise the new antigens = can’t produce the antibodies to destroy it. (This is know as antigenic variability)
• there’s lots of variations of a pathogen = impossible to create vaccines for all of the variants, e.g. there’s 100s of variants of the common cold virus
• certain pathogens ‘hide’ from the immune system: concealing themselves inside cells or living in places out of reach (such as inside the intestines, e.g. cholera)
• individuals may have moral/religious/medical objections to having one

Question 13

What are some of the ethical issues that are brought up about the production and use of vaccines

Answer 13

• ethical issues surrounding using animals to produce existing ones and developing new ones
• side effects = can cause long term harm. Difficult to balance the side effects vs developing a disease that can cause more harm
• who should vaccines be tested on? How should trials be carried out? What extent can we ask individuals to accept the risks in the interests of public health?
• should we trial vaccines with unknown health risks only in countries where the disease is?
• should vaccines be compulsory (heard immunity can’t be achieved otherwise), or only when there’s an epidemic?
• should expensive vaccine programmes continue when a disease is nearly wiped out, even if it means less money for the treatment of other diseases