The store, which had been open for several hours, closed as soon as they were told of one of their staff members, they called partners by the firm, had contracted the virus.
This was confirmed by a Waitrose spokeswoman.
'We can confirm that a partner in our Rohais branch has tested positive for Covid-19,' the spokeswoman said.
'Although this partner has not been working since 3 April, we have carried out a deep clean of our shop.
'We are working closely with the States of Guernsey and will take whatever action is necessary for the health and safety of our partners and customers.'
Waitrose had put in measures to help protect both customers and their staff. This included limiting the number of customers in their shops at any one time, encouraging contactless and cashless payment methods, having dedicated marshals per store to help manage queues who would remind customers of the two-metre social distancing rule, as well as introducing floor signage in all shops to ensure customers keep two metres apart when queuing at checkouts and at welcome desks.
To help staff they also installed screens at the checkouts, along with fewer checkouts open to maintain social distancing and partners had been given the option to wear a protective visor.
