You know that gallon of hand sanitizer you bought for flu season? You're probably using it wrong.

According to a new study from the Society for Healthcare Epidemiology of America, simply slathering your hands with sanitizer for a few seconds won’t do much without some extra attention and elbow grease.

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The study, published by the Society for Healthcare Epidemiology of America, compared a three-step process recommended by the Centers for Disease Control and Prevention with a more intricate one from the World Health Organization. A total of 120 health care professionals at an inner-city teaching hospital in Glasgow, Scotland, took part in the study.

The CDC recommends applying hand sanitizer to one palm, rubbing hands together and continuing to do so until both hands are dry. Meanwhile, the WHO’s process, which takes 7.5 seconds longer on average, involves rubbing sanitizer palm to palm, rubbing each palm from back to front while interlacing fingers, rubbing the backs of fingers against opposing palms, and rubbing around each thumb and the centers of each palm.

Scientists discovered that the WHO’s recommendation was much more effective at ridding hands of germs. Since hand hygiene is the "most important intervention" between you and your co-worker's sinus infection, the study says it's worth those extra 7.5 seconds to avoid contracting and spreading illnesses.