For COVID-19, hand washing with soap and water or sanitizer with > 60% alcohol (ABHR - Alcohol based handrub) is recommended as per CDC & WHO.

Some facts on HandRub

Among hand sanitizer, ABHR (greater than 60% ethanol or 70% isopropanol) should be used than those with a lower alcohol concentration or non-alcohol-based hand sanitizers. It inactivates viruses that are genetically related to, and with similar physical properties as, the 2019-nCoV.

Usually ABHR have final concentrations of 80% ethanol or 75% isopropyl alcohol concentrations.

Benzalkonium chloride based hand rub are also available but it has less reliable activity against certain bacteria and viruses than either of the alcohols.

Chlorhexidine is not mandatory in handrub for killing virus & it should not be used outside hospital settings to avoid misuse and resistance.

Apart from Alcohol, emolliants ,hydrogen peroxide (H2O2) & water is required in hand rub as per WHO recommendation.
-Low concentration of H2O2 is added in Hand rub to inactivate contaminating bacterial spores in the solution and is not an active substance for hand antisepsis.
-Glycerol: used as humectant, but other emollients may be used for skin care.
(Provided that they are cheap, widely available and miscible in water and alcohol and do not add to toxicity, or promote allergy)
There are several differences between soap and water & hand sanitizer.

Pros of Soap and water

Soap and water removes all types of germs as well as chemicals and dirt from hand while hand sanitizer removes certain types of germs only.

Soap with water also acts by removing germs and dirt mechanically.



Cons of ABHR - Hand sanitizer

ABHD is not effective for certain microbes like Cryptosporidium, norovirus and Clostridium difficile etc.

Alcohols have very poor activity against protozoan oocysts, certain non-enveloped (non-lipophilic) viruses, and bacterial spores

Hand sanitizer may not be as effective when hands are visibly dirty and greasy.

Hand sanitizer is not effective to remove harmful chemicals from hand like pesticide and heavy metals etc.

Correct technique :

Another thing to keep in mind using hand sanitizer is keeping it over hands until dry rather than wiping them off & apply in sufficient volume.
Wash hands as per WHO steps
Scrub/rub your hands for at least 20 seconds , it will be dried in 20-30 seconds. (One can sing Happy Birthday song twice to complete >20 seconds.)



Use Soap and water only in following conditions

Hands are visibly dirty
Blood or other body fluid stained
Before, during and after preparing food
Before eating food
After using toilet
Before and after caring for someone who is sick with vomiting or diarrhea
Before and after treating a cut or wound
After changing diapers, or cleaning up a child who has used the bathroom
After touching an animal, animal feed, or animal waste
After handling pet food or pet treats
After touching garbage

References:


Show Me the Science – When & How to Use Hand Sanitizer in Community Settings
Code:
https://www.cdc.gov/handwashing/show-me-the-science-hand-sanitizer.html
Code:
https://www.cdc.gov/handwashing/hand-sanitizer-use.html
Hand Hygiene Recommendations for healthcare providers : CDC
Code:
https://www.cdc.gov/handhygiene/providers/index.html
Compounding alcohol-based hand sanitizer during the COVID-19 pandemic - Download Infographic
Code:
https://go.usp.org/l/323321/2020-04-24/35lxqv/323321/105669/Compounding_Alcohol_Based_Hand_Sanitizer_During_COVID_19_Pandemic_Infographic.pdf
Guide to Local Production: WHO-recommended Handrub Formulations
Code:
https://www.who.int/gpsc/5may/Guide_to_Local_Production.pdf
WHO Brochure of hand hygiene
Code:
https://www.who.int/gpsc/5may/Hand_Hygiene_Why_How_and_When_Brochure.pdf