Don't bathe hamsters with water, and don't feed them raw water, foods with too much water, sugar or salt, and foods that are too sour or sticky.
Reasonable and sufficient feeding environment can prolong the life span of hamsters, and the average life span of normal hamsters can reach 2.5 to 3 years.
As for the spread of germs, anything can spread germs as long as it is not absolutely sterile. Even without hamsters, the air already contains a lot of bacteria, and the three immune systems of the human body can isolate most viruses and bacteria. As long as you remember to wash your hands after playing hamster, you don't have to worry about being dirty.