Week 3 - Immunity and Vaccines

• Natural: ○ Active (encountering antigen) ○ Passive (antibody transfer by natural means) • Artificial: - Active (vaccination) - Passive (antibody transfer by artificial means)

Immunity gained through illness and recovery, enters the body naturally

Immunity acquired from antibodies passed in breastmilk or through placenta

Immunity gained through a vaccine

Immunity gained through antibodies harvested from another person or an animal

• Live, attenuated (weakened) microbes • Killed whole microbes • Portions of microbes • Toxoids (inactivated toxins)

Live, attenuated vaccine would give the most effective response

Because they often provide lifetime immunity without the need for boosters

A vaccine stimulates your immune system to produce antibodies, exactly like it would if you were exposed to the disease. After getting vaccinated, you develop immunity to that disease, without having to get the disease first.

Needed to intensify the immune response of a killed whole bacterial cells, toxoids, inactivated microbes or sub-units as the immune system does not respond as powerfully as when a live attenuated vaccine is given.

Results when most of a population is immune to the disease, If most people are immune then they won’t be carriers. It is protecting those who aren’t immune

• Hypersensitivity reaction • Autoimmune disorder • Immuno-compromised • Reactions to transported or foreign tissues • Chronic inflammation

Allergy is a hypersensitivity to an environmental antigen. Anaphylaxis is the most severe & rapid reaction. It is life- threatening as it causes constriction of the bronchial smooth muscle and oedema of the throat

The immune system attacks the body’s own cells when it fails to recognise ‘self’ e.g. rheumatoid arthritis

Persons are at risk from minor infections; - Very young, elderly, severe illness , stress

Including blood transfusion reactions, donated organs etc

Underlying cause of asthma or arteriosclerosis

• The new-borns’ immune system becomes stronger during encounters with both harmful & harmless microbes. - excessive use of antibiotics & antibacterial agents may prevent normal development (over use of antibacterial products e.g. Dettol) • With advancing age people become more susceptible to infection - Response to vaccines and infections is decreased as less antibodies are produced resulting in a slower response. - Older people are therefore more susceptible to infection

Controlling viral diseases

• Immunocompromised people (could cause disease) - Pregnant people (Risk to the fetus)

• Most commonly Redness and swelling at the injection site, pain and mild fever • Rare occasions - allergic reactions

More likely to produce strong antibody & cellular response & long-lasting immunity.

Minute risk that the organism might mutate back to a virulent strain.

Does not provoke the immune response as strongly as a live microbe.