Ok, I will go with that, how much deterioration in effectiveness, then what is to be done to correct the effect, why was this not taken into consideration to begin with, further, why is a professor of veterinary pathobiology bringing it up; this is why I am a bit critical on topic.
His ewe died leaving him with spare time?
It may be because the tests to date have been done on animals with human tests to follow.
I posted this because it looks like something people should be aware of.