one health lecture 2- viral vaccines Flashcards
what is a vaccine?
Boost the immune system to protect against
an infection with the aim of eradication
what is a prophylactic vaccination?
-Prevention
-Develop immunity in a susceptible host
what is therapeutic vaccination?
-Post-exposure
-Augments or accelerates immunity in someone previously infected
what is in vaccine?
-active ingredients
-adjuvants
-preservatives and stabilisers
-water
-residual traces
what are at risk groups?
Extra vaccines for at risk groups
-Underlying medical conditions
Pregnant
-Infants born to HepB infected mothers
-Infants born in high TB incidence area
whats recommended for those coming to uni
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
what is herd immunity?
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
what is the reproduction number?
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
what do the values for the reproduction number mean?
An outbreak is expected to continue if R0 has a value >1 and to end if R0 is <1
what are the candidates for global eradication?
polio virus= Transmitted via person-person contact
measles virus and rubella virus = Transmitted via direct contact or droplet spread
what are the advantages for replicating( living) viral vaccines?
Stimulate antibody and T cell responses
Can stimulate mucosal immunity
A single vaccine may be enough to give protection
More durable immunity?
what are the disadvantages for replicating( living) viral vaccines?
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
what are the advantages for non replicating( non-living) viral vaccines?
No risk of infection
Safe!
Can be quicker to produce
what are the disadvantages for non replicating( non-living) viral vaccines?
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
what is the only pathogen to be eradicated?
smallpox
how was the eradication of smallpox achieved?
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
what is the history of eradication??
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?)
