Why is soap and water so effective at preventing a virus from spreading? Soap dissolves the outer layer, or membrane, of a virus. Without this membrane, the virus falls apart and becomes inactive. The virus detaches from the skin and falls apart in soapy water. Skin is a rough surface, which means you need to rub and soak to ensure maximum reach. Wash your hands for at least 20 seconds each time and dry your hands thoroughly. When soap and water is not practical, disinfectants, alcohol wipes and gels are also effective.