Ann: Phase III prophylaxis trial for CS-8958 , page-21

"The trial demonstrated the protective efficacies of a single, inhaled dose of CS-8958 of 20mg and 40mg as measured by the Risk Reduction Rate (RRR) were 43.7% and
43.2% respectively but were lower than the preset RRR endpoint of 70%.

The possible reasons offered for the lower protective efficacies were the low infection rate within families in the placebo group (8.6%) and the growth in public awareness, resulting in the use of other preventative infection measures during the 09H1N1 pandemic."

With only an 8.6% infection rate in the placebo group, thats a small infection rate to be tested against i.e. 43.5% reduction equates to an infection rate of 4.6% in the those taking the dose. A small infection rate is very suspectible to random variations in the percentages if the sample population is small.

Does anyone know the sample populations of the 3 groups in the trial?

Regards

SP