Re: Question about cold
Well, it's supposedly about 48 hours between when you're exposed to a cold virus and when it multiples in your system and then symptoms develop. So...maybe 1-3 days or so..
However in my experience, generally I've been exposed to a cold and then a WEEK later I'll finally get the first symptoms but it's definitely that one exposure and not someone else later on who I was exposed to. I think it depends on the exact strain of virus. There are just millions and they all cause slightly different incubation and symptom patterns I think.
Possibly a person who has a cold is contagious for a few days...I think the same time as the general incubation period of 1-3 days BUT bear in mind that they are MOST contagious right before symptoms start, so...unfortunately if you're exposed to someone a lot and then 1-2 days later they've got a visible cold, they were probably most contagious just beforehand when nobody knew they were getting sick. (or technically already sick).
It's because the virus multiples so quickly in your throat and nose and you have no symptoms at this stage because the body doesn't know anything is really wrong yet...which is why you end up getting sick in the first place, because your body lets its guard down while all this is happening. It's only once the virus has taken over (and thus you are most contagious while this is going on) that you start to experience the sore throat, sneezing, nose problems, etc. And it's not the cold that causes this, it's your body reacting to the cold, trying to get rid of it from your system by explusion of various fluids (ew). So the symptoms are your body fighting off the cold.
The reason I think people assume it's the symptoms that are the cold and that it means people are most contagious, is because it's really the symptoms that spread the cold...it's more difficult to pass on a cold if you're never sneezing or coughing, you know? Even though the majority of colds are actually spread by touch rather than airborne.
So yeah, a person who has a cold and has had it actively (meaning with symptoms) for like, 5 days, shouldn't be contagious anymore, even if they have symptoms still...unless their symptoms get worse, in which case it could have moved into the chest or sinuses and could be a secondary bacterial infection. Then they'd be contagious again.
Hope this has helped!