Unless there is some new data that I'm not aware of, there has been nothing to suggest that a kid under 12 is at any higher risk of severe illness from Delta than they were from the prior variants. The risk for prior variants to that population was extremely low and factually lower than the risk to them from the flu in a normal year. If that information changes then I'll change my stance. I've said from the beginning that if children were heavily affected by COVID many of my opinions would be different.
Now, I'd like somebody to educate me regarding masks and the Delta variant. If we assume that the lab experiments translate to the real world and the mask blocks 70% of the virus leaving the infected person and 70% of the virus entering the non-infected person, that means that 9% of the virus particles make it through the journey.
Now, it has been reported that the viral load for somebody infected with Delta is 1000 times what it was for prior variants. 1000 times 9% is 9000%. That means that for Delta, 90 times the amount of virus will make the journey, through masks that made it through the with prior variants through masks. If I'm doing the math correctly, that means that for Delta, there will be 8.1 times the amount of virus that makes the journey WITH masking than made the journey without masking of the other variants. Therefore, why would we expect masking to have any significant effect on Delta.
Obviously, the real world numbers will be higher due to variable materials, fit and how people are wearing the masks.