We all learn how to behave socially, and the rules vary based on our cultural backgrounds. We may shake hands, high-five, hug or air-kiss when greeting others. In some cultures, you never chew with your mouth open, while in others nobody really care. For some, it’s fine to toss money to the person you’re paying; for others that is extremely offensive.
In the current COVID situation, until there are effective vaccines or treatments, the only effective safeguard we have is being careful in how we interact with others: how we greet each other, how we behave in groups, how we project expectations of others' behaviour, and how we react to unexpected situations.