Lesson 49 - Vaccines and active/passive immunity

Question 1

What are vaccinations?

Answer 1

Involves injection of antigens that have been isolated from a dead/attenuated microorganism. This induces a primary immune response in an individual (production of memory cells), without them suffering the symptoms of the disease.

Question 2

Describe how giving a HPV vaccine leads to production of antibody against HPV. (4 marks)

Answer 2

1. Vaccine contains antigen from HPV;
2. Displayed on antigen-presenting cells;
3. Specific helper T-cell detects antigen and stimulates specific B-cell;
4. B-cell divides by mitosis/forms clones to give plasma cells;
5. B-cell/plasma cell produces antibody;

Question 3

What is herd immunity?

Answer 3

When a sufficiently large proportion of the population has been vaccinated to make it difficult for a pathogen to spread even to those not immunised.

Question 4

When do vaccines not work?

Answer 4

• Certain individuals with defective immune systems
• Individuals may develop the disease and then infect others
• When pathogens mutate frequently - difficult to develop a vaccine against them
• Pathogens that hide from the immune system somehow
• Individuals may have objections against vaccines: religious, ethical or medical reasons

Question 5

Describe antigenic variability in terms of vaccinations

Answer 5

A pathogen may mutate frequently, which can cause its surface antigens to change. The vaccine then suddenly becomes ineffective because the antibodies of the immune system are no long complementary to the antigens.

Question 6

Ethical concerns of using vaccines are…?

Answer 6

Use of animals to test vaccines
Side effects, so some people don’t want to take the vaccine relying on herd immunity
Vaccines are tested on human volunteers
Economical concerns
With a new epidemic, there would be a rush to receive the vaccine and difficult decisions would have to be made on who would be 1st to receive it

Question 7

What are the 2 types of immunity?

Answer 7

Passive immunity: introducing/inserting monoclonal antibodies into an organism from an outside source - no contact with the pathogen or its antigens. E.g. maternal antibodies (natural) or monoclonal antibodies (artificial)
Active immunity: involves direct contact with the pathogen or its antigens, stimulating the body’s immune system to produce its own antibodies. E.g. infection (natural) or vaccination (artificial)

Question 8

Describe the difference between passive and active immunity (5 marks)

Answer 8

1. Active involves memory cells, passive doesn’t;
2. Active involves production of antibody by plasma/memory cells;
3. Passive involves antibody introduced into body from outside;
4. Active is long term, because antibody produced in response to antigen;
5. Passive is short term, because antibody given is broken down;
6. Active can take time to develop/work, passive is fast acting;

Question 9

Features of a successful vaccination?

Answer 9

• Must be financially available
• Must have few side-effects - if any!
• Must be ways of producing, storing and transporting the vaccine
• Must be ways of giving (administering) the vaccine properly - may involve training staff
• Must be available in sufficient quantities to vaccinate most of the population to result in herd immunity