COVID-19 spreads mainly among people who are in close contact (within about 6 feet) for a prolonged period.

https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/social-distancing.html

(where a prolonged period of time is defined as >30 min.)

Or from a 4 day old preprint Covid-19 case cluster study by Prof Streeck in Germany.

"So far, no transmission of the virus in supermarkets, restaurants or hairdressers has been proven,""

"There is no significant risk of catching the disease when you go shopping. Severe outbreaks of the infection were always a result of people being closer together over a longer period of time."

"One pattern we are seeing across the globe is that wherever there was singing and dancing, the virus spread more rapidly."