Can someone just be a carrier of the cold or flu virus without showing symptoms?
Yes people can be carriers of these flu and cold viruses Some of them never show any sign of being sick Their immune system prevents this. They can transfer these germs to other though and this is what spreads these viruses. Be careful and be safe.
I believe cold and flu can lie dormant in your body up to 15 days before/after your sick without showing symptoms and can be transferred to another person.