While it can be a useful measure. Everything must be taken in context. Sure 6% is 50% better than 4% (relatively) but in reality it is not much more than a rounding error in absolute terms. I mean 12 vs 10 is only a 20% difference. They could wait until it was 1% vs 3% and they would have a 200% RRR but it wouldn't be meaningful.
Wonder what the "Relative Risk" reduction of death will be in the DCVAX arm a5 5 years? 200-300%? 5 vs 15-20?