The UK is currently studying the use of trained dogs to detect the odour — from clothing — of a coronavirus asymptomatic case. The expectation is that this non-invasive method will rapidly screen, at 250 persons per hour (per dog, but dogs do get tired, it’s not magic) at barrier locations such as trains and airplanes.
Perhaps India can investigate whether cows can do a similar job. The great advantage is that nobody will beef about false positives, and the authorities will blindly overlook all possibilities of false negatives.
Anyhow, to return to remote testing, yes, a scan must analyse at the molecular level. It can’t be analogous to gas chromatography, though, as that will mainly (only?) detect elements, not compounds, apart from the thought of vapourising blood in the eyeball being a little intimidating. Perhaps some form of crystallography?
Yes, that is my point, that the infection is being fought, it need not be a patient who is fully cured. While the death rate is fortunately low, those are people who are probably don’t have the right immune systems: however, the percentage of people who don’t need advanced care is also low, so it ought to be easy to obtain reference samples of the right antibodies, that can be used in a non-invasive non-destructive test kit.