Perhaps, but if you think about how systems like this work today, for example scanning ID at the entrance to a nightclub or bar. One way something like this is

Perhaps, but if you think about how systems like this work today, for example scanning ID at the entrance to a nightclub or bar. One way something like this is likely to be implemented is by validating a ticket or access card/token with a saliva swab. This is just too easy and attractive an opportunity for data collection to be passed up by some operators with business models that monetise the data as a revenue source.