Module 5 - Population Health

Question 1

What are some host factors that affect disease?

Answer 1

• age
• gender
• genetics
• behaviours
• exposures
• immunity

Question 2

What are some agent factors that affect disease?

Answer 2

• pathogenicity
• infectivity
• immunogenicity
• infective dose

Question 3

What are some environmental factors that affect disease?

Answer 3

• social (crowding)

- physical (barriers, climate)

Question 4

List 3 things that the objectives of an immunization program depend on

Answer 4

1 - availability and efficacy of vaccines
2 - capacity to reach target populations
3 - epidemiology of disease

Question 5

What are 3 possible objectives of an immunization program?

Answer 5

1 - eradication of disease
2 - elimination of disease
3 - control of disease

Question 6

Define: latency

Answer 6

time from infection with an infectious agent to the minimum level to transmit the disease

Question 7

Define: incubation period

Answer 7

the time from exposure to the causative agent until the first symptoms develop (this is characteristic for each disease agent)

Question 8

Define: symptomatic period

Answer 8

time from when the patient displays symptoms to the point when they have ended

Question 9

Define: Infectiousness

Answer 9

Proportion of exposed persons who become infected

Question 10

Define: Pathogenicity

Answer 10

proportion of infected people who develop clinical disease

Question 11

Define: Virulence

Answer 11

proportion of people with clinical disease who become severely ill or die

Question 12

Describe the spread of a disease

Answer 12

Once exposed, a person is either infected or not infected

Once infected, there is either disease or no apparent disease

Once sick, there is either a severe disease or not severe disease

Question 13

What is herd immunity?

Answer 13

when the vaccinated portion of the population provides protection to unprotected individuals

Question 14

What is the basic reproductive rate or R0?

Answer 14

number of secondary cases generated from a single infectious case introduced into a susceptible population

Question 15

If R0 > 1 ……?

Answer 15

disease will increasingly spread (epidemic)

Question 16

If R0 = 1 ….?

Answer 16

disease will stabilize (epidemic)

Question 17

If R0 < 1 ….?

Answer 17

disease will disappear

Question 18

If R0 = 15, how many people need to be immunized using herd immunity to prevent the disease becoming epidemic?

Answer 18

1 - 1/R0
1-1/15 = 0.94

so 94% of the population needs to be immunized to be able to protect the rest of the population (i.e. herd immunity)

Question 19

What are some economic barriers to vaccines?

Answer 19

• cost of the vaccine
• time away from work for vaccine administration
• accessibility to immunization and immunization professionals

Question 20

What are some system-based barriers to vaccines?

Answer 20

• increasingly complex immunization schedules
• different schedules across Canada
• inadequate documentation
• lack of a unique immunization record
• absence of standing orders
• inadequate tracking of immunization delay

Question 21

What are some socially-related barriers to vaccines?

Answer 21

• lack of education of immunization providers and/or recipients
• inadequate communication of the complications of vaccine-preventable diseases
• increasing focus on the potential adverse effects of immunizations