Vaccines Flashcards
Give the 3 main objectives on vaccinations
- To protect select high risk groups
- To contain an infection within a population
- To eradicate an infectious agent
What is the difference between active and passive vaccination?
Active - stimulates the immune system with an antigenic substance to generate immunity
Passive - introduces antibodies against the disease from another immune person
What are the disadvantages of active and passive immunity?
Active - if live vaccine may contract the disease and SEs
Passive - doesn’t build up the bodys immune memory
Name the 6 types of vaccine in terms of their delivery
Live attenuated Live unattenuated Whole killed organism Disrupted toxin Antigenic components Manufactured virus-like particles
How does a vaccine contain an infection within a population?
Reduces the number of infections
Interrupts transmission to humans
Generates herd immunity
Prevents outbreaks/epidemics
How do you calculate the immunity of a vaccine?
Efficacy x Uptake
Eg: if efficacy is 90% and the uptake rate is 100% the overall immunity rate would be 0.9
What are the reasons for why someone may not be vaccinated?
Anti-vacc
Immunocompromised
Young children
Allergies
What can impact effectiveness of a vaccination?
Wrong age of patient Wrong site Deterioration of vaccine Incorrect preparation of a reconstituted vaccine Immunological status of the patient
What is vaccine failure?
When an infection occurs despite someone receiving a full course of an effective vaccine
What can influence the uptake of a vaccine?
Public perception
Cost
Efficiency
What is herd immunity?
Indirect protection for susceptible populations as a result of the majority of a population being vaccinated
What is the herd immunity threshold?
1 - s (% of the population who are susceptible)
List as many factors as you can that should be considered if implementing a new vaccine programme
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
Give the 3 broad barriers to successful vaccination programmes in developing countries
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.
What is R?
The Basic Reproduction Number: how many secondary cases can be infected by each infectious person
What can R be affected by?
Characteristics of the infecting organism - infectivity and incubation period
Population characteristics - mixing patterns, demographics, population density
How is R calculated?
R0 x S
What is R0?
The number of secondary infections produced in a totally susceptible population
What is S?
The % of the population who are susceptible
Name as many vaccine preventable diseases as you can
Measles, polio, diphtheria, tetanus, pertussis, TB, Hep B, HiB, Rubella, Yellow fever
How could you increase uptake rates of a vaccine?
- Identify unvaccinated children - through GP registers/school etc.
- Providing accessible services - school-based/community-based clinics
- Longer term sustainability - check ups
What information may be collected to monitor a vaccination programme?
Cases of the disease
Ordering and supply information of the vaccine
Vaccination status of children
Routine collection of coverage rates
How can vaccines be better implemented in developing countries?
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
