During pandemic, I thinking about how to optimize or minimize contact to reduce virus expose. This depend on many factor like a person work characteristic, health, age... For example we should prioritize shipper, shop keeper... to get vaccinated first. At housing block, we let some people to get groceries and then distributed to smaller family or individual. ... https://www.sciencedirect.com/science/article/pii/S2468042720300245 https://www.visualcapitalist.com/the-math-behind-social-distancing/ https://www.nature.com/articles/s41591-020-0883-7