Question

Hand sanitizer is one of the best means of reducing the spread of?

Answer 1

Germs! of course it says it on the label.

Answer 2

Germs. 

Washing hands with soap and water is the best way to reduce the number of microbes on them in most situations. If soap and water are not available, use an alcohol-based hand sanitizer that contains at least 60% alcohol. collapsed.

https://www.cdc.gov/handwashing/show-me-the-science-hand-sanitizer.html