One reason I didn't interact as much with friends at the wedding as I would've liked is that it's possible I was exposed to measles last week.
It's unlikely that I was actually exposed. And I think I had measles as a kid, so I think I'm immune. (But I didn't have the vaccine, and I don't know where my childhood medical records would be, so I'm not sure I had the disease. I'll be taking the test today to find out if I'm immune, but apparently the results may take five days to reach me.) And if I was infected, I think it's unlikely that I would have been infectious only a few days later. (I gather that you become infectious around the onset of the fever, a week or two after being infected, but I was having a hard time getting reliable information on that; the nurses I was talking to kept telling me infected people are contagious before symptoms appear, but I think they meant the rash symptom specifically, which comes a few days after the fever.) And I gather that something like 95% of Americans have had either measles or the vaccine. So the chances of my infecting someone were extremely low.
And yet, spreading measles at a wedding really seemed like bad form. So, just to be sure, I warned everyone to stay well away from me, so the only people who I got to hug were people who were certain that they'd either had measles or had the vaccine.
If I had thought there was a significant chance of my having measles, I would've stayed home from the wedding. According to the CDC, it's possible to catch measles by touching an infected surface, up to two hours after the surface's contact with the infected person. Yikes.
So I was being overcautious, and possibly being cautious in ways that wouldn't have been effective if caution had been needed. But I was having a hard time getting very much detailed information about various things, and I figured better to be overcautious than undercautious.
I especially stayed well clear of a pregnant friend. I was told in various contexts that pregnant women can't receive the vaccine, but I wasn't at all clear on whether it's more dangerous for a pregnant woman to be exposed if she's already immune than it would be for anyone else. I would think that her immune system would protect the fetus, but I'm having a hard time finding information about that. Though I now see that it's very strongly implied on the CDC measles vaccine FAQ page, under "Why is MMR vaccine given after the first birthday?"
Really, that was the most frustrating thing about all of this--my information sources were often incomplete, ambiguous, and/or of uncertain reliability. The nurses I talked with could answer some of my specific questions, but for most of them they had to ask a doctor, and the particular doctor they were supposed to ask was unavailable, and anyway it was like playing Telephone--I would ask a question, they would take it to the doctor, they would call me back a while later and tell me what the doctor said, the answer would result in my having another more detailed question, repeat.
The main CDC page on measles provides pointers to a lot of useful info, but for some reason that page wasn't turning up in my search results when I was looking in a hurry on Friday. And it still doesn't quite answer all my questions.