I started out politely asking people to keep their distance, politely pointing out the one-way markers in the aisle, but I was met with indifference and, in one case, someone who frowned at me and rudely waved me off. Now I'm barking at shoppers who are clearly ignoring the distancing rules to keep them from brushing by me in the aisles when there is room to distance or when they're walking the wrong way. I know some may be absent-minded and some may not have noticed the arrows everywhere, but I've had it. I'm just barking: "Keep your distance!" or "You're going the wrong way!"
I haven't said the following to anyone, but I will if I get push back: "Six people in my family contracted the virus. My 40-year-old cousin is in the hospital* and my 73-year-old aunt is hospitalized on a ventilator. She's expected to die. So I'm not screwing around. Keep. Your. Distance."
So far, barking at people seems to make them much more malleable and accommodating, even without the family health report, which doesn't surprise me. I don't enjoy causing distress in others and, as a rule I avoid it, but they'll recover. If it stings, it may help them be a more conscious of the rights and safety of others, even if they don't care about their own safety.
*My cousin was previously hospitalized with the virus and was quite ill for several weeks. She had just gotten her strength back last week, but this week began to feel ill again and tested positive again.