Setting a non-inferiority margin of 5% seems clinically and statistically relevant; and yields a sample size that makes the execution of the study feasible within the time frame and with the resources available. Choosing a smaller margin than 5% may be too tight requiring large sample size of over 2000 per arm which might not be feasible and achievable within the time frame; a larger margin than 5% may be too liberal to compare the public health impact of these interventions.