Migros, Aldi and Lidl have all introduced the software, which uses automatic sensors to count the number of people in the market as they enter and restricts entry to anyone else when the maximum number is reached. 

Automatic sensors are set up at the entry and exit to the store. New customers are told via a red or green traffic light as to whether they can enter the market or if they have to wait. 

The automatic sensor operates anonymously, removing concerns of some customers and consumer groups that an app would need to be downloaded and used so that customers could be tracked when they entered the store.

A spokesperson for Lidl told Swiss news outlet Watson that employees are now freed up to focus on supermarket work, rather than being stationed at the entry and exit areas to count customers. 

The access controls were introduced at supermarkets in Basel, Lucerne, Vaud, Neuchâtel and Freiburg and will continue to be rolled out in other areas across April. 

Supermarket chain Coop has not introduced the software and will continue to count by hand, but has not ruled out introducing a similar system in the future, reports 20 Minutes. 

Pursuant to coronavirus social distancing guidelines, each supermarket in Switzerland can only have a maximum number of customers.