The Mexicans who seem to be most affected (to the extent of dying) are healthy young people. I would suspect that most of them are not of primarily Indian descent, since most of the indigenous people or their very close descendants live in the more outlying areas and are not well off. Middle class urban people in Mexico are mostly of European descent, which includes Spanish, French, Irish, and German; in addition, a fair number of Mexicans have Jewish ancestry.
We’ll have to wait for a socio-demographic statistical breakdown...
I would suspect that most of them are not of primarily Indian descent, since most of the indigenous people or their very close descendants live in the more outlying areas and are not well off.