Not random people, no, but it's a useful signal for "that person is probably contagious right now so I'll give them a wide berth".
I have got into the habit of telling people close to me, and it gives them a chance not to avoid getting a cold, but to mitigate the impact by treating the symptoms before they've really emerged.
I have got into the habit of telling people close to me, and it gives them a chance not to avoid getting a cold, but to mitigate the impact by treating the symptoms before they've really emerged.