Hugs, I hope your little guy is better soon. My Dr always said that they shouldn't be around anyone within 24 hours of a fever. If symptoms are present more then likely he is still contagious. Same with our schools, not to send children that have had a fever within 24 hours. So if he still has one I wouldn't get him around anyone else.
I personally think the best prevention is the vaccine. Even the healthiest person when exposed will get it. It can get serious fast, even for adults. With someone high risk in the family I definitely would get the family shots.
I have always had my kids vaccinated for the flu yearly starting when they were old enough to recieve it. You cannot get the flu from the vaccine, it is clinically proven. They do the mist now too. Very easy and they don't have to have a shot. Their insurance I have on the kids covers the vaccine, I pay the $20 for mine as it is worth that! I work in child care so it is very important I am protected. If there are no egg allergies it is safe. My kids prefer no more shots so we started the mist which is a live virus but they have never been sick because of it.
I have always had the vaccine myself for over 12 years now. Kids that come down with some strains it can be life threatening or turn respitory very fast which is why they promote kids getting it and changing the age limit to all children now.
I personally just don't mess around with that stuff. The vaccines don't cover every strain and some years it is hit or miss, but both of mine are in school and exposed to a lot of other kids so I just think it is another safety measure. I have never had it nor have my kids. Thank God.
I would say if the rest of the family can, to get vaccinated next year as you can be a carrier and maybe not get as sick but can bring it home if not vaccinated. It is such a simple vaccine to give you that added security Again, it isn't fool proof, however it is more of a protection I would think then taking some other preventative care ongoing. Hugs, I hope your son is better soon.