I'm not sure anyone has proof beyond experience at this point. It SEEMS that you cannot get more buffs (infections) after you've been infected the first time. That being said, it doesn't necessarily mean you had to get all buffs at the exact same moment. It APPEARS to be either that, (getting multiple buffs at the exact same moment) OR that you had to get them in the same activity. Meaning that, once you leave the activity in which you were first infected that's it... you cannot pick up any other buffs. While you are in the activity you MAY be able to pick up different buffs from different sources. I have brilliance and magnificent. I got both from one crucible match. I'm not sure if both buffs came from the same player, but I received both in that one match. I have tried everything I can think of (nightfall, heroic strikes, daily strike, daily/weekly crucible events, patrolling, crucible, more crucible, even more crucible.... ) to add other buffs with zero luck after that one crucible match where I first got infected. Also, there were definitely guardians in some of these events carrying buffs I did not already have. If it were possible, I should have been able to pick up the different buffs. Didn't happen. Again, this is just what I've gathered from reading different peoples'experiences. I hope it's incorrect. I'd still like to catch all the infections to benefit from the buffs they give. Let me know if you discover something different! Good luck getting the infections you want... I can't believe I just said that... lol