NSES Content Standard F  
Science in Personal and Social Perspectives: Personal health 
Grades K-4, page 140 

Individuals have some responsibility for their own health. Students should engage in personal care--dental hygiene, cleanliness, and exercise--that will maintain and improve health. Understandings include how communicable diseases, such as colds, are transmitted, and some of the body's defense mechanisms that prevent or overcome illness. 

Benchmark 6E The Human Organism: Physical Health
Grades K-2, page 144
Some diseases are caused by germs, some are not. Diseases caused by germs may be spread by people who have them. Washing one's hands with soap and water reduces the number of germs that can get into the body or that can be passed on to other people.

Benchmark 6E The Human Organism: Physical Health
Grades 3-5, page 144
If germs are able to get inside one's body, they may keep it from working properly. For defense against germs, the human body has tears, saliva, skin, some blood cells, and stomach secretions. A healthy body can fight most germs that do get inside. However, there are some germs that interfere with the body's defenses.