
Then I thought about it some more and realised it must mean something else. Of course, what it really means is that the medics treated some protesters and then they were convicted to 15 years in jail for their efforts. It's a pity the journalist didn't say it more clearly.
Technically, we can say that it is ambiguous whether the adverbial 'for up to 15 years' modifies jails or treated. But it would be easy to rephrase the sentence to eliminate this source of confusion.