Question

Q2.1: Your population is 500. With 60% of the population vaccinated, what is the initial number of susceptible people s(0)? ___200_ Q2.2: What proportion of susceptibles became sick with smallpox during this epidemic?_40%_ Q2.3: What is the lowest value for proportion to vaccinate that protects the entire population from a smallpox epidemic? Q2.4: If some individuals in the population have recovered from a previous smallpox infection, how would the required minimum proportion to vaccinate change?__

question about 2.3 and2.4

Answer 1

Answer.

Q2.3 - According to herd immunity relationship.

Vc=E-(E/R0)

Where Vc = critical vaccination level (proportion of population vaccinated to achieve herd immunity.)

E = vaccine effective against the transmission.

R0 = Basic reproduction number.

So, let the effectiveness of vaccination (E) is 100% or 1,

and R0, it can vary population to population so let minimum value for infected population recovered is 3.

so putting value

Vc = 1-(1/3) = 67%

So around 67% is the lowest value for proportion to vaccinate that protect the entire population.

Q2.4 - If some individuals have recovered from smallpox, Then the value of R0 (Basic reproduction number) became change as a result Vc (critical vaccination level) became change.