I would imagine it would be since I just saw a report that 4 layers of quilters cotton is equal to the protection ability of a surgical mask - or able to block 79% of the germs. They suggest you hold the fabric up to a light and if you can see through ii, or see individual threads, then it's not going to be much use at stopping the virus.

I have been using it in some of the masks I am making. It is definitely thicker than lots of other fabrics I have.

My daughter just took a sheet (100% cotton) that they have not used. She read that somewhere. Makes sense.
I would imagine that Kona Cotton would be a High Quality Quilters Cotton.

Yes they are.