one health lecture 2- viral vaccines

Question 1

what is a vaccine?

Answer 1

Boost the immune system to protect against
an infection with the aim of eradication

Question 2

what is a prophylactic vaccination?

Answer 2

-Prevention
-Develop immunity in a susceptible host

Question 3

what is therapeutic vaccination?

Answer 3

-Post-exposure
-Augments or accelerates immunity in someone previously infected

Question 4

what is in vaccine?

Answer 4

-active ingredients
-adjuvants
-preservatives and stabilisers
-water
-residual traces

Question 5

what are at risk groups?

Answer 5

Extra vaccines for at risk groups
-Underlying medical conditions
Pregnant
-Infants born to HepB infected mothers
-Infants born in high TB incidence area

Question 6

whats recommended for those coming to uni

Answer 6

For coming to University you are advised to have:
The MenACWY vaccine
You can still ask your GP for this vaccine until your 25th birthday.
2 doses of the MMR vaccine

Question 7

what is herd immunity?

Answer 7

When a large proportion of a population is vaccinated, it is harder for an infectious disease to spread
Protection for communities
In particular those who cannot be vaccinated

Doesn’t offer high level of protection to individuals

Decreases unnecessary deaths
Breaks the chain of transmission

Percentage of population to achieve herd immunity varies with each disease

Question 7

what is the reproduction number?

Answer 7

Basic reproduction number/ ratio/ rate

Epidemiologic metric used to describe the contagiousness or transmissibility of an infectious agent
Estimated with complex mathematical models

Affected by several factors
-Biological
-Sociobehavioral
-Environmental

Question 8

what do the values for the reproduction number mean?

Answer 8

An outbreak is expected to continue if R0 has a value >1 and to end if R0 is <1

Question 9

what are the candidates for global eradication?

Answer 9

polio virus= Transmitted via person-person contact
measles virus and rubella virus = Transmitted via direct contact or droplet spread

Question 10

what are the advantages for replicating( living) viral vaccines?

Answer 10

Stimulate antibody and T cell responses
Can stimulate mucosal immunity
A single vaccine may be enough to give protection
More durable immunity?

Question 11

what are the disadvantages for replicating( living) viral vaccines?

Answer 11

Restoration of increased virulence (polio)
continual testing necessary
Persistence of vaccine virus in the immunosuppressed
Can be pathogenic (i.e. cause disease)
Cell culture not always possible and may be low yield
Limited shelf life
need stored at low temperatures

Question 12

what are the advantages for non replicating( non-living) viral vaccines?

Answer 12

No risk of infection
Safe!
Can be quicker to produce

Question 13

what are the disadvantages for non replicating( non-living) viral vaccines?

Answer 13

May be less immunogenic
Induce a less efficient cytotoxic T cell response
May require adjuvants
Often require boosters
May not stimulate a local IgA mucosal response

Question 14

what is the only pathogen to be eradicated?

Answer 14

smallpox

Question 15

how was the eradication of smallpox achieved?

Answer 15

Factors favouring smallpox eradication through vaccination

Effective and safe vaccine
Cheap, heat stable and 1 dose
Lifelong natural immunity induced
Short period of communicability
Transmission easily curtailed
Highly characteristic clinical syndrome
Distinctive rash
Easy and reliable means of diagnosis
No nonhuman/or environmental reservoir
Key for eradication
Genetically stable causative agent
Seasonality of occurrence

Question 16

what is the history of eradication??

Answer 16

Attempts to vaccinate date from 1695
‘With the exception of safe water, no other modality, not even antibiotics, has had such a major effect on mortality reduction and population growth’
A Short History of vaccination, Vaccines, 3rd Edition, S and S Plotkin

Alternative?
The nose was plugged with powdered smallpox scabs laid on cotton wool
Powdered smallpox scabs were blown into the nose
A healthy child wore the undergarments of an affected child for several days
Apiece of cotton containing contents of a smallpox vesicle was stuffed into the nose
White cow fleas were ground into powder and made into pills (first oral vaccine?)