Question special

Many thanks for the opportunity to discuss this important research. I find trial designs very interesting, and I noted with interest your 2:1 intervention:placebo ratio. I'd be interested to know more about the rationale behind that.

I naively assume an imbalance like this will reduce power and therefore require a larger sample. However, since you anticipated a much lower rate of dengue in the vaccinated population, would it have provided a statistical benefit in increasing precision of estimating that small proportion?

I also wondered if you anticipated benefits for recruitment if the chance of active intervention was increased?