Immunology

Question 1

What are the 5 requirements for the successful eradication of a virus?

Answer 1

1. Availability of an effective, attenuated vaccine
2. Antigen Stable Virus (Single Antigenic Type)
3. Absence of Asymptomatic Cases or Persistent Carriers
4. Absence of an animal reservoir
5. Public Cooperation

Question 2

What is the risk of Severe allergic reactions or anaphylaxis in vaccines?

Answer 2

Highly rare: approximately 1 in a million doses

Question 3

What is herd immunity?

Answer 3

When the entire population are protected from an infectious disease when a critical percentage of immune individuals is reached

Question 4

How does herd immunity work?

Answer 4

1. Low number of unvaccinated people in the population - limits initial infection.
2. Limits spread of disease within a population by being unable to transmit infection easily host to host
3. Protecting susceptible members not yet exposed to the disease or unvaccinated

Question 5

What is the critical threshold for herd immunity?

Answer 5

The % of the population that require vaccination to effective stem an outbreak from occurring. This differs depending on the virulence, transmission vector and geography of the population.

Typically herd immunity requires 80% (rubella) to 95% (measles)

Question 6

What are common reasons for vaccine refusal?

Answer 6

1. Belief that VPDs are mild/self-limited
2. Concerns about side effects
3. Distrust of Medical Establishment

Question 7

Why might there be an increase in vaccine preventable diseases?

Answer 7

1. Anti-vaccination Movement
2. Waning Efficacy of Certain Vaccines
3. Pathogen Adaptation
4. Travel of individuals to areas where disease is endemic