In Law Help!!!!

So I already have been dealing with a crazy MIL, long story on how she's been but it's been a ride so far. Anyway, my SO family will be coming from out of town all over and I know they are wanting to see LO. We have a scheduled family picture which I'm not bothered by but I'm worried about everyone wanting to pick him up and hold him. He will only be a month old at the time and so he won't have his first round of shots. I've tried to keep holding and such limited to immediate family because I know their health more extensively. I don't know everyone's health that is coming into town and I don't want to risk my little one catching anything. But I also don't want to be the person who withholds her child and gets the guilt trip for it. I know my MIL won't understand because she's already made comments about how she wants him to come by her work and meet her coworkers! Like random people I have NEVER even met. 

Has anyone else had to deal with telling people no? If so can anyone give me advice on how to do it without being a stuck up mother? If that's even possible lol