There is no source. I don't want my elderly parents to go out even to get important things like groceries. They are lucky that my sister and I are shopping for them. Not all elderly can do this. They are taking a risk every time they go out for the basics. If there was a way we could develop a quick app that monitors queues or parking lot vacancies or some other indication of crowd size, these folks could go during low risk times. Or if we could try "elderly time slots" when the store or service was only open to the elderly (like first thing in the morning before contagion of the masses arrives for the day) that could also reduce risk for these folks that don't have a choice.