Each autumn, as seasonal viruses begin to circulate, the debate over the best method for hand hygiene—soap or hydroalcoholic gel—comes up again. In France, public health guidelines consider soap washing as the primary method for hand hygiene, while hydroalcoholic gel is seen as a practical alternative in specific circumstances. This distinction is based on the different ways each method works to reduce the spread of germs. Soap works by using surfactant molecules that break down the lipid envelopes of viruses, effectively destroying them. This chemical action is enhanced by the physical act of rinsing with water, which removes dirt, debris, and any remaining germs. According to Santé publique France, hands are the main way infectious agents spread, responsible for about 80% of infections. For this reason, thorough handwashing is emphasized as a critical preventive measure. Hydroalcoholic gel, which typically contains 60% to 85% ethanol, is effective at killing a wide range of viruses and bacteria on clean, dry hands. However, it is less effective when hands are greasy, dirty, or covered in organic matter, as it disinfects but doesn’t clean. The World Health Organization (WHO) notes that hydroalcoholic gel is not effective against certain alcohol-resistant pathogens like norovirus. For these reasons, soap is considered the more reliable option when hands are visibly dirty or after activities that expose them to contaminants. Proper use of hydroalcoholic gel is essential for it to work well. Applying too little or not allowing it to dry completely can reduce its effectiveness. The gel should cover all surfaces of the hands and be left to dry naturally, without wiping. Additionally, it is recommended to use it only when soap and water are not available, such as when traveling on public transport or after touching high-contact surfaces like railings or money. Once access to a sink is available, returning to soap washing is advised to ensure thorough cleaning and skin protection.