In medicine, especially emergency medicine, "rationing" is called triage.  

You get bashed with a sudden overload, you eliminate those who will recover without your aid; those most likely to need your aid to survive; and lastly those who aren't going to make it anyhow.

I don't know of any difference in severity, mortality based on ethnicity, but that doesn't mean there isn't some rational basis in the triage process. 

I believe economic status does bear on mortality and severity; and that does have and ethnicity factor. The average "white American families" as whole have 6-10 times the net worth of 'black American families'.

Sputter and spit that America isn't a racist culture but the data are the data.