The Centers for Disease Control and Prevention echo this sentiment . Your first choice for cleansing should be soap and water . Scrubbing for at least 20 seconds (that's about the length of two renditions of "Happy Birthday") will remove germs, and any dirt or debris that could also contribute to you getting sick. If you don't have any access a sink, then use a hand sanitizer that contains at least 60% alcohol. This will kill infectious microbes like, but it won't go that extra mile of removing grubbiness.