Vaccination

Vaccination is an example of what type of immunity?

Artificial active immunity.

How may a vaccine be given?

• Via the mouth.

• As an injection into the bloodstream.

Briefly explain how a vaccine works.

The vaccine promotes a primary immune response without causing the disease. Memory cells are produced so that when the individual is exposed to the disease, a secondary response occurs so symptoms do not develop.

What are the main differences between a primary immune response and a secondary immune response?

• No latent period in the secondary immune response – antibodies are produced immediately.

• The secondary immune response is faster than the primary.

• A higher level of antibodies is produced which remain at a higher level for longer than in the primary immune response.

What are the main types of vaccines?

• Killed- contains microorganisms which have been killed with chemicals or heat. The pathogen cannot cause an infection but the antigens can trigger an immune response.

• Attenuated- contains weakened strain of bacterium/virus. May infect the patient but it is easily fought off by the immune system.

• Toxoid- contains inactivated toxins.

• Subunit- contains specific antigens or sub-units of a microorganism (especially viruses) can create an immune response.

Describe the features of a vaccine which successfully protects against a disease.

• The antigen must be highly immunogenic- this means that a single dose must provoke a strong immune response. It would rapidly make a large number of antibodies, specific for a particular antigen.

• There should be only one antigenic type of the pathogen- so only one vaccine is needed and the antibodies formed are able to attack all of them.

• They have no or few side-effects which are mild in nature.

• They lead to long-lasting immunity from the disease.

Organisms with many antigenic types (e.g. influenza) require…?

Annual vaccination programmes against the most common antigen types for that year. Even so, it is not 100% effective.

What is herd immunity?

This is the idea that if enough people are immune to the disease through vaccination, there is a reduced reservoir of the pathogen in the population. This provides protection to people who are unable to be vaccinated because of compromised immune systems or illness.

State some of the ethical issues connected to vaccination programmes.

• The cost and effectiveness of the vaccine.

• The protection of individuals and the community and whether vaccination should be compulsory e.g. for health care workers.

• The rights of individuals to refuse vaccinations; this may particularly apply to parents choosing not to vaccinate their children.

• Real and perceived side effects.