Survey being conducted on the radio this morning “Is it rude if someone asks you if you’ve been vaccinated against COVID?”

I think it's a mildly rude thing, like asking me if I smoke cigarettes. I would likely reply "none of your business!".

I don't consider it rude.  I'm proud to say that I got vaccinated.  In fact, I even went and did it twice!

I would not find it rude if someone asked me that whether it was someone I knew or not.  It's not as though they're asking me how much money I earn.

Not at all. It was just a survey. Go ahead and ask me.

Just my opinion, of course:

Someone known to you - no

Complete stranger - depends on who initiated the conversation about Covid.  If they just ask you at random, it's rude.  But if (say) you strike up a conversation while waiting in line, and are talking about Covid, then it's not rude because it's part of the topic you're already discussing.

Employer - no

School staff (I assume for you or your kid) - no

Business - depends on if they have a policy, such as customers don't have to wear a mask if they've been fully vaccinated.  I'd assume they would probably want to see proof of vaccine, if they fully intend to follow the policy.

Yes, if the asker is outside of one's immediate family or friends close enough to know the question will not offend.   

Depends on who the person is and their reaction when I say no and I have no intention of getting it. 

Right now it's a popular topic of conversation among people I know.  Did you get it, when did you get it, where did you get it, how did you react to it? So, it's hardly rude in that context.  I might ask a stranger who is about to step into my personal space and is unmasked whether he or she is vaccinated.  Maybe it's rude, but it's my health and I will protect it. I think there is a whole new protocol about offering and asking for vaccination status until the pandemic is truly behind us.