The epidemic curve is generally exponential during the early stage of an epidemic, presenting a challenge in identifying parameters of mathematical models that incorporate multiple control measures. This presents a major hurdle in estimating the effectiveness of non-pharmaceutical interventions, which are crucial to control the outbreak during this stage. In the first part of the talk, we show how to use a novel pair-approximation model to disentangle the effect of contact tracing from other control measures such as business closure and social distancing in Ontario. Our results show that the daily counts of new cases, cases diagnosed via contact tracing, and symptom onsets are necessary in this evaluation. In the second part, we present a cross-regional comparison of the effects of age-specific interventions in Toronto, Calgary, and Vancouver. We fitted an age-stratified SEIR model to daily new cases in each city in 2020 to estimate the change in the transmission rate in each period when public health interventions changed. Our results agree with some previous findings that, in all cities, a modest strengthening of the interventions in adults may have similar effects as school closures. However, keeping schools open in Spring 2020 has a larger impact in Calgary than the other cities, possibly because the transmission rates in Calgary were faster than the other two cities during the period.