In a class of 19 students, the average rate of contact between students is 13 pe
ID: 181671 • Letter: I
Question
In a class of 19 students, the average rate of contact between students is 13 per 30 seconds (or 0.433), and contacts always lead to infection (infection/contact = 1). • What is the transmission rate? • What is R0? • If R0 is calculated by the equation R0 = (contacts/time) * (infections/contact) * (time/infection), And the “virulence” of the disease is such that death occurs 10 seconds after infection, calculate R0. • At least how many people in the class should be vaccinated to prevent a disease outbreak in the class, if the vaccination is 100% effective?
Explanation / Answer
The average rate of contact between students in a class of 19 students is 13 per 30 seconds i.e. 0.433. contacts always lead to infection (infection/contact = 1) i.e. 100% chance of getting infection with contact. The population is of the fixed size (19). The rate at which susceptible individuals become infected is called the transmission rate So the transmission rate is 1/people*days i.e. Transmission rate=contact rate =0.433.
RO (basic reproduction number) is expected number of secondary cases produced by a infection in a susceptible population and is calculated as product of transmissibility, rate of contact between infected and suceptible population and duration of infectiousness i.e. (contacts/time) * (infections/contact) * (time/infection). It is no dimention number.
Virulence of the disease is such that death occurs 10 seconds after infection. So RO=(13/30)*(n/13)*(30/n)=(13/30)*(1/13)*(30/1)=1
At least how many people in the class should be vaccinated to prevent a disease outbreak in the class, if the vaccination is 100% effective?
Conventionally, it is assumed that if R0>1 the outbreak generates an epidemic. None of the total population becomes infected when an infection is sub-critical. So atleast 7 should be vaccinated to prevent a disease outbreak in the class.