For years I have used this basic castille hand soap to keep the harmful germs off the skin, while preserving that protective coating and giving the immune system a boost through the essential oils used.
Liquid castille soap (can purchase from local health food store, Bulk Apothecary, Amazon or Mountain Rose Herbs)
Essential oil of choice - I like to use an herbal antiviral blend such as Thieves from Young Living, SpiceC from Butterfly Express or Shield from Mountain Rose Herbs. Or you can use a single or blend for a particular scent such as citrus or floral. This is the fun part of making your own soap.
Fill your foaming soap dispenser a quarter full of liquid castille soap. Depending on the size of your bottle and how strong you like your soap to smell, start with 10-20 drops of essential oil and adjust from there. Fill the remainder of the bottle with water and screw on the top. Give it a gentle swish around and you are ready to start foaming.