I picked a random strain from last year, and I don't know if I just picked an unpopular one, but it's been nearly 24 hours and I'm still not infected. Should I give up and pick a different strain? Survival is very confusing to me now: I haven't been around for it since 2012, and this is not how it used to work.

Have you gone and found a thread for the people with the virus you picked, so they can bite you? If you hover the link of the one you chose, you can see the official name for it at the end of the url (for 2015 only, I think the older ones have somewhat descriptive urls, but not the official names). I think you'll still get infected on your own eventually but I'm not sure how long it takes.

Oh man I didn't even notice those, duh. Thank you!!!

You're welcome, glad I could be somewhat helpful ^_^