"To those who felt they were exempt from this blanket ban because they were so special and important, you weren't and aren't.
"Frankly, Hawke's Bay Rugby [is] appalled that you would threaten the health of your young players just for your own ego," Mr Macdonald said.
Mr Macdonald said nothing should ever override the health and safety of youngsters in the province.
"People have to realise that a game of rugby is not important in the scheme of things when we're talking about health and safety."
He preferred to think there would "never be a next time" with a crisis of the stomach bug proportions for the union to test the resolve of such people.
"It's been a bit of a learning curve for us as well," he said.
"At the end of the day, we're relying on common sense and decency of people to [deal with] what is potentially a health problem.