Have you ever seen a cup of coffee just after the coffee beans are ground and tightly packed into a cylinder as they are infused with steam. Under pressure, the scolding water works its magic through the grounds and brewed coffee begins to trickle into the cup. If the cup was preheated, the coffee remains hot as it fills. Afterwards, the barista floats a dollop of foamed milk gently on the surface. Voilà.

You may wish to sip the hot coffee, allowing the taste of sweet milk to enter your mouth at the same time. The two temperatures, the binary flavors, sweet and tart, and the dual textures of wet coffee and foamy milk add to the sensation. Aah. It is said that only wine has a more complex flavor.
Okay, now think about contact tracing.
Imagine if you were asked to remove all of the milk from that cup of coffee just after a spoonful of the foamed had been floated on the coffee. It would be difficult but it could be done. Using a spoon to remove a majority of the floating foam, you would have to pick at the rest, pulling out tiny fragments here and there. That’s what contact tracing would be like, picking out one or two people at time who may have had contact with others who had exposure to the coronavirus.
Now, imagine if you had stirred the foamy, floating island of milk into the coffee until they are one taste, one homogenous color, one temperature and a single texture. Contact tracing, then, would be like trying to separate the blended foam from the coffee. It couldn’t be done. At this late date, contact tracing may be useful in reaching out to the sick and contageous but will do little to stem the tide of this pandemic. Another methodology is needed.