What do you think about me telling my friend he should get himself vaccinated for measles?
Has he not gotten vaccinated yet? Why do you think you should tell him to get vaccinated?
He sucks at making his own decisions, and is against vaccinations, so I wanted to help him out.
You should not tell your friend what is best for his healthcare. Your friend may resent you for prying into his business and you may offend him by recommending something he has already considered. It would be better to advise him to talk to doctors about it.
I think that his choice to be against vaccinations is dumb so I'm going to tell him to get the measles vaccine anyway.
While you may not agree with his choice, it's not your place to tell him he should get vaccinated, especially knowing that he actively disagrees with getting vaccines. This is a life choice he's made, and he will likely resent you for prying into his health care decisions. If you really want to, you should start up a conversation and offer valid information contrary to his beliefs.