Why are elderly people now being prioritized in grocery stores during the coronavirus outbreak?

I watched the news that supermarkets in USA open market early for elder people because of coronavirus. I think it is a good idea for them. Pandemic of coronavirus makes panic buying all over the world. Many people gathered to supermarket and then we could see only empty shelves. Elder people are hard to win this competition and they are also hard to use online market. So, I think it is good consideration because this supermarkets have sufficient stuff. Also, elder people are more weak about diseases than young people. if there are some infected people when many people gather to supermarket, it is very dangerous to elder people. So, I think it is a way to prevent infection. Our society is trying to effort to protect social weak people. For example, there are seats for social weak people like pregnant women, disabled persons in public transportation. I think it is a way to considerate them.