I was wondering if someone didn't have a phone, however, their parents did, wouldn't that be different since you don't go to the same place as your parents do. For example, assume that Person 2 has COVID and doesn't have NOVID, Person 2's parent, which we'll assume is Parent 2, doesn't have NOVID. Now assume that you go to swimming(or play basketball or whatever) with Person 2. NOVID wouldn't necessarily track that right? So, contrary to the answer Po gave at his LMT talk, you wouldn't necessarily know you have a "1".