One of the most powerful weapons against the H1N1 virus is summed up in a three-word phrase you first heard from your mother: wash your hands.

Many recent studies have highlighted the importance of this most basic hygiene measure. In one study, scientists counted the times the students touched their faces, documenting every lip scratch, eye rub and nose pick. On average, the students touched their eyes, noses and lips 47 times during a three-hour period, once every four minutes. The importance of this study is that hand-to-face contact has an impact on health. Germs can enter the body through the membranes of the eyes, mouth and nose.

Young children benefit from hand washing too. In a study of 6,000 elementary school students in California, Delaware, Ohio and Tennessee, students in classrooms with hand sanitizers had 20 percent fewer absences due to illness. Teacher absenteeism in those schools dropped 10 percent.

Regular soap and water and alcohol-based hand sanitizers are both effective in eliminating the H1N1 virus from the hands. In February, researchers in Australia coated the hands of 20 volunteers with copious amounts of a seasonal H1N1 flu virus. The concentration of virus was equivalent to the amount that would occur when an infected person used a hand to wipe a runny nose. When the subjects did not wash their hands, large amounts of live virus remained even after an hour, but using soap and water or a sanitizer virtually eliminated the presence of the virus.

Frequent hand washing will not eliminate risk of getting the H1N1 virus or any virus for that matter. When an infected person coughs or sneezes, a bystander might be splattered by large droplets or may inhale airborne particles. Still, it is a good idea to wash your hands regularly even if you’re not in contact people who are obviously ill.

For all these reasons, the Centers for Disease Control and Prevention with other health organizations around the world, urge frequent hand washing with soap and water or alcohol-based hand sanitizers. They also emphasize some advice you may not have heard from your mother: cough or sneeze into the crook of your elbow, not your bare hands.