Consider a Susceptible-Infected-Recovered (SIR)-model . Briefly explain the terms the 'Basic Reproduction Number', R0, and the 'Effective Reproduction Number, R(t). What useful information do they provide about the pandemic? Consider an economy under a pandemic where there remains a very large susceptible population, S. Clearly explain how each of the following two scenarios (i) public health measures (e.g. mitigation and suppression strategies) and (ii) a sudden arrival of an effective vaccine or an effective anti-viral medication is likely to affect R(t). In light of your response, briefly comment on the particular ongoing challenge in affecting the value of R(t) in Canada