To prevent colds and flu, parents and kids should not share tubes of toothpaste. Each family member should have their own tube of toothpaste.
Kids and adults can avoid getting sick by not putting ANYTHING into their mouths. Cold/flu germs can be found on items people commonly put into their mouths such as fingers, fingernails, pencils, erasers, pen caps, toys, and etc. Children get into the bad habit of putting things in their mouths at a young age and can follow them through adulthood. Teach your children willpower and persistence to defeat this habit.