The contents valet have known for a long time that a 70% alcohol gel or solution is better than 90% alcohol for killing encapsulated viruses. 70% has a little water in it and can denature and break the encapsulation, thus destroying the virus within.
A higher concentration of alcohol will (in effect) “cook” the exterior wall of the virus causing it to “crust over” and protect the virus within.
62% alcohol (like some hand sanitizers) may not be enough, 99% can dry out the membrane and turn it into a shield, 70% has worked with other viruses it is the concentration that physicians use in an operating theater – contents professionals know this – workers without proper training, don’t.
Please don’t misunderstand, we aren’t saying that alcohol kills COVID-19. We are simply pointing out that encapsulated viruses (COVID-19 is an encapsulated virus) are known to deactivate when exposed to 70%) — and often don’t when exposed to higher or lower percentages.