Reading the story all I can think of is the possibilities. Suspend the particles into and disperse with aerosol in public places and then scan for indicators you want as they walk through or by detectors. You could set it all up to report to individuals anonymously, but the idea of what a future of health care might be should include a system which requires no action on the patients.

The privacy concerns could be immense or moot, but many would trade for the convenience