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The Covid-19 pandemic weighs heavily on global health systems. In the current absence of effective therapies and vaccines, adequate hygiene measures are essential to prevent the spread of the virus. Wash your hands frequently, as seen, is one of them.
Hand sanitizers alcohol-based are the only known means of rapidly and effectively inactivating a wide range of pathogenic microorganisms, including coronavirus.
Alcohol-based cleaners, WHO formulations
WHO, World Health Organization (or WHO, World Health Organization) shows how to prepare hand sanitizers with two do-it-yourself formulas. Using readily available ingredients, emergency permitting, which are endowed with a fast-acting, broad spectrum microbicidal ability. (1)
A scientific study being published has demonstrated the effective ability of alcohol-based disinfectants to inhibit the virus, with specific tests on the formulations suggested by the WHO. (2)
Ingredients
Ethanol. It is pure ethyl alcohol (when the ethanol concentration reaches 95%, it actually behaves in the same way as a pure compound),
Hydrogen peroxide 3%. It is 10-volume hydrogen peroxide. Used at low concentration, it helps eliminate contaminating spores in solutions and containers. The active ingredient is not in itself suitable for sterilizing hands.
Isopropyl alcohol (or isopropanol alcohol, referred to as 2-propanol). Also known as white alcohol, it is one of the most common organic compounds of the alcohol family. Due to the dangerousness of the pure substance, it is rarely sold in its pure state, but inserted in specific formulations for various purposes.
Glycerol. It is used as a humectant, to increase the tolerability of the product. However, other skin care emollients can be used, provided they are miscible in water and alcohol.
Formula 1, composition
Ethanol 96%, 8.333 ml (8,33 liters)
- Hydrogen peroxide 3%, 417 ml
- Glycerol 98%, 145 ml.
Formula 2, composition
- Isopropyl alcohol 99,8%, 7.515 mL (7,515 liters)
- Hydrogen peroxide 3%, 417 ml
- Glycerol 98%, 145 ml.
Preparation
1) Pour the alcohol into a 10 liter tank.
2) Add the hydrogen peroxide.
3) Add the glycerol.
4) Top up the bottle / tank, up to 10 liters, with boiled and cooled tap water.
5) Mix the solution by shaking gently, if necessary, using a scoop.
6) Immediately divide the solution into smaller containers (eg plastic bottles of 100 or 500 ml) and place the bottles in quarantine for 72 hours before use. In this way, in addition to reducing the risk of fires or dangerous fumes, there is time to destroy any spores present in alcohol or bottles.
Important
WHO recommends It is strongly recommended that you do not add additional ingredients to the above-mentioned formulas other than those indicated.
Handle with extreme care, since alcohol is highly flammable and can produce dangerous fumes.
Label and instructions
- Formula to disinfect hands recommended by WHO
- For external use only
- Avoid contact with eyes
- Keep out of reach of children
- Production date and batch number
- Use: apply a spoonful of the solution and cover all the surfaces of the hands. Rub your hands until dry
- Composition: ethanol or isopropanol, glycerol and hydrogen peroxide - Flammable: keep away from flames and heat sources.
Effectiveness of WHO formulas on Covid-19, scientific confirmation
The two formulas of disinfectants recommended by the WHO have been the subject of recent specific experimental tests, which have confirmed their effectiveness against SARS-CoV-2. (2) A concentration of at least 30% ethanol or 2-propanol is sufficient to inactivate the virus within 30 seconds. In particular:
- formula 1 WHO, based on 85% of ethanol, efficiently inactivated the virus with reduction factors (RF) of <5,9 and concentrations between 40 and 80%,
- formula 2 WHO, based on 75% of isopropanol, demonstrated an improved virucidal effect at low concentrations, with complete viral inactivation and reduction factors of <5 at a minimum concentration of 30%.
Martina Novelli and Dario Dongo
Note
(1) https://www.who.int/gpsc/5may/Guide_to_Local_Production.pdf
(2) A. Kratzel, D. Todt, P. V'kovski, S. Steiner, ML Gultom, Tran Thi Nhu Thao, N. Ebert, M. Holwerda, J. Steinmann, D. Niemeyer, R. Dijkman, G Kampf, C. Drosten, E. Steinmann, V. Thiel, S. Pfaender. (2020). MedRxiv (study pending peer-review). Efficient inactivation of SARS-CoV-2 by WHO-recommended hand rub formulations and alcohols. https://www.biorxiv.org/content/10.1101/2020.03.10.986711v1.article-info
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
