Vaccines + Active and Passive immunity

What is the primary immune response?

The response when a specific antigen enters the body for the first time.

What is the secondary immune response?

The second time that same specific antigen enters your body in which case you've developed immunity to the antigen and rapidly produce antibodies and have an instant immune response.

What is a vaccination?

The injection of antigens that have been isolated from a dead/attenuated microorganism which induces a primary immune response in an individual, without them suffering the symptoms of the disease.

How do vaccines lead to the production of antibodies and memory cells against the pathogen?

- Vaccine contains pathogen with antigen which gets engulfed and displayed on an antigen-presenting cell during phagocytosis.

- A specific helper T cell detects the antigen and stimulates a specific B cell to divide by mitosis.

- Some of those B cells will become memory B cells or plasma cells which will produce antibodies against the specific antigen.

What’s herd immunity?

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.

When do vaccines not work?

- Certain individuals with defective immune systems-> may either not develop immunity or may develop the disease

- Individuals may have objections against vaccines-> religious, ethical, medical

- Antigenic variability

What is antigenic variability and why would vaccines then not work?

The pathogen mutates which can cause its surface antigens to change. The vaccine then suddenly becomes ineffective because the antibodies of the immune system are no longer complementary to the antigens.

What are some ethical concerns with using vaccines?

- Use of animals

- Side effects

- Who should be tested?

- Should trials only occur in specific countries?

- Should it be compulsory?

- Economical concerns

- The greater good vs individual health risks

What are the 2 types of immunity? Define them and provide examples.

1. Passive immunity- introducing/inserting monoclonal antibodies into an organism from an outside source so no contact with the pathogen or its antigens e.g. maternal antibodies, monoclonal antibodies.

2. Active immunity- direct contact with the pathogen or its antigens, stimulating the body's immune system to produce its own antibodies e.g. infection, vaccination.

What are some differences between active and passive immunity?

Active:

- Antibodies secreted by plasma cells

- Longer term because memory cells are created

- Takes longer to develop

Passive:

- Antibodies introduced into body from outside

- Short term because no memory cells are created and antibodies eventually break down

- Fast acting

What are some features of a successful vaccination?

- Must be financially available

- Must have few side effects if any

- Must be ways of administering the vaccine properly

- Must be available in sufficient quantities to vaccinate most of the population to result in herd immunity