There are 4 major types of germs. They are bacteria, viruses, fungi, and protozoa. They can invade in plants, animals, and people. Sometimes they can make you sick. Bacteria can reproduce outside of the body, or within the body and cause infections.
Influenza is contagious so it can be spread easily from person to person because of eye droplets or fluids sent through the air when someone sneezes or coughs.
Cold and flu can remain alive in the environment for up to 48 hours. Other germs like the Norovirus virus( diarrhea and vomiting) can live up to 12 days outside the body.