I either read it wrong or wrote it wrong. I read it as it cut it down to 1 in 5 not the other way around.
It's more how articles on this are being written.
100 people on ventilators, 40 will die on average.
Give a 100 people on ventilators the new drug, 27 will die on average. Those 13 out of 40 lives saved is how they got the 1 in 3 figure.