Vaccines

Question 1

Give the 3 main objectives on vaccinations

Answer 1

1. To protect select high risk groups
2. To contain an infection within a population
3. To eradicate an infectious agent

Question 2

What is the difference between active and passive vaccination?

Answer 2

Active - stimulates the immune system with an antigenic substance to generate immunity

Passive - introduces antibodies against the disease from another immune person

Question 3

What are the disadvantages of active and passive immunity?

Answer 3

Active - if live vaccine may contract the disease and SEs

Passive - doesn’t build up the bodys immune memory

Question 4

Name the 6 types of vaccine in terms of their delivery

Answer 4

Live attenuated
Live unattenuated
Whole killed organism
Disrupted toxin
Antigenic components
Manufactured virus-like particles

Question 5

How does a vaccine contain an infection within a population?

Answer 5

Reduces the number of infections
Interrupts transmission to humans
Generates herd immunity
Prevents outbreaks/epidemics

Question 6

How do you calculate the immunity of a vaccine?

Answer 6

Efficacy x Uptake

Eg: if efficacy is 90% and the uptake rate is 100% the overall immunity rate would be 0.9

Question 7

What are the reasons for why someone may not be vaccinated?

Answer 7

Anti-vacc
Immunocompromised
Young children
Allergies

Question 8

What can impact effectiveness of a vaccination?

Answer 8

Wrong age of patient
Wrong site 
Deterioration of vaccine 
Incorrect preparation of a reconstituted vaccine 
Immunological status of the patient

Question 9

What is vaccine failure?

Answer 9

When an infection occurs despite someone receiving a full course of an effective vaccine

Question 10

What can influence the uptake of a vaccine?

Answer 10

Public perception
Cost
Efficiency

Question 11

What is herd immunity?

Answer 11

Indirect protection for susceptible populations as a result of the majority of a population being vaccinated

Question 12

What is the herd immunity threshold?

Answer 12

1 - s (% of the population who are susceptible)

Question 13

List as many factors as you can that should be considered if implementing a new vaccine programme

Answer 13

Burden of the disease
Severity of the disease
Prevalence of the disease
Host susceptibility to the disease
Alternative prevention/treatment methods
Effectiveness of the vaccine
Side effects
Cost-effectiveness
Transport/storage of the vaccine 
Uptake rate
Immunisation schedule 
Delivery of the vaccine 
Interactions with existing vaccinations
Number of doses required
How long the vaccine lasts
Timelieness

Question 14

Give the 3 broad barriers to successful vaccination programmes in developing countries

Answer 14

Health/financial system troubles- lack of staff/resources/funding
Political barriers - lack of effective leadership, corruption
Geographical/social-cultural -hard to reach communities, traditional beliefs etc.

Question 15

What is R?

Answer 15

The Basic Reproduction Number: how many secondary cases can be infected by each infectious person

Question 16

What can R be affected by?

Answer 16

Characteristics of the infecting organism - infectivity and incubation period
Population characteristics - mixing patterns, demographics, population density

Question 17

How is R calculated?

Answer 17

R0 x S

Question 18

What is R0?

Answer 18

The number of secondary infections produced in a totally susceptible population

Question 19

What is S?

Answer 19

The % of the population who are susceptible

Question 20

Name as many vaccine preventable diseases as you can

Answer 20

Measles, polio, diphtheria, tetanus, pertussis, TB, Hep B, HiB, Rubella, Yellow fever

Question 21

How could you increase uptake rates of a vaccine?

Answer 21

1. Identify unvaccinated children - through GP registers/school etc.
2. Providing accessible services - school-based/community-based clinics
3. Longer term sustainability - check ups

Question 22

What information may be collected to monitor a vaccination programme?

Answer 22

Cases of the disease
Ordering and supply information of the vaccine
Vaccination status of children
Routine collection of coverage rates

Question 23

How can vaccines be better implemented in developing countries?

Answer 23

Integrate with other PHC services
Expand vaccination coverage of the whole population
Ensure regular supply of vaccines
Strengthen the cold chain
Train health personnel
Promote community participation 
Incorporate health education activities
Introduce monitoring and evaluation