Here in Taiwan we have an app that notifies us if we've been in contact with a registered positive case, and how long the contact was. Though it doesn't say where the contact took place or at what time. My wife and I headed down to the south of Taiwan to visit her family over the last few days, and then we got an alert on the app that shows we had around 30 minutes of contact with a positive case last Saturday. That was probably on the train, which is an enclosed space, so my wife was naturally nervous about getting infected. So we both tested ourselves last night.
Standard procedure: we poked our nostrils, mixed it with the test solution, dripped it onto the test strip, and waited for fifteen minutes. Then at the end, I checked our strips, and said to my wife, "I see two lines!"
Shocked, she replied, "What???"
I clarified, "One line for you, one line for me."
And then my wife smacked me upside the head.