I read on one of the US forums ages ago that there are two distinct types of medical exam paper sold there and that only one of them is suitable for pattern tracing. Of course I can't remember the details now
but I do know that when I searched for it in the UK I could only find the non-recommended one on sale.
I did get hold of some stuff last year, however, that was sold for use on exam beds/ beautician's couches etc made from a sandwich of SMS polyester fibres (Spun Bond/Melt Blown/Spun Bond) - coincidentally the sort of thing that is used inside medical masks. It's quite soft, fine and very lightweight, nevertheless, I thought I'd give that a go for tracing dolls clothes patterns and it has both traced and sewed up remarkably well. I'll probably continue to use my spot and cross paper for tracing and keeping patterns but I may well cut them out in the SMS poly for fitting purposes and then transfer adjustment back to the traced one.