19. Virus Epidemiology Flashcards
what is R0
the average number of secondary cases per case in a totally susceptible population
what happens if R0:
>1
=1
<1
> 1 = cases increase
= 1 = cases stable
< 1 = cases decrease
what was the R number for measles in an unvaccinated population
15
what is key to reducing exposure
breaking the transmission chain
- protective clothing
- isolating patients
who is responsible for dealing with infective people that enter the country
public health england
what are the 3 measures taken in response to an outbreak
- contact tracing
- breaking the transmission chain
- stopping infected individuals entering the country
what is case fatality rate a proportion of
the number of positive cases to the number who died
what is the difference between an endemic and an epidemic disease
endemic = steady number of new cases as time progresses = no great peaks or troughs
epidemic = number of new cases increases rapidly
is ebola endemic or epidemic
epidemic
- although studies suggest it could become endemic
define outbreak
localised infections to which we know the site of the initial case
how can we reduce R0
- treatment (reduce duration of infection)
- barriers (reduce transmission risk)
- isolation (reduce contact rate)
what is the formula for net case reproduction number
R0 x the proportion of the population still susceptible
how can we reduce R (net case reproduction number)
reducing the amount of people still susceptible
define herd immunity
the proportion of the population that needs to be immune for a disease to become stable
what is vaccine efficacy a measure of
a measure of how good a vaccine is at preventing disease
