At any given point of time, a disproportionate number of shoppers in a store are super-shoppers - people that shop more often than the average person and for lo

At any given point of time, a disproportionate number of shoppers in a store are super-shoppers - people that shop more often than the average person and for longer periods of time. Those people are also more likely to have caught Coronavirus before. Without even getting into online ordering, false positives, etc...this phenomenon alone may confound the test results.