Tesco says a number of staff at one of its supermarkets have tested positive for coronavirus.
The cases were found among workers at its Extra store on Ocotal Way in Swindon.
The town is on the government's coronavirus watchlist after a recent rise in cases centred around an Iceland supermarket distribution centre.
Tesco says the affected staff are now self isolating.
Confirming the cases at the Ocotal Way Extra store, a Tesco spokesperson said: "We have introduced extensive measures across all of our stores to help keep everyone safe, including protective screens at every checkout, social distancing signage and regular deep cleaning."
Swindon was added to the coronavirus watchlist on 7 August.
The list covers places where extra measures such as local lockdowns or increased testing may be introduced, but health officials say the main outbreak at the Iceland centre is now under control.
A spokesperson for Swindon Borough Council's Public Health department said: "We are aware of the very small number of Covid-19 cases affecting staff at the Tesco store.
"Our Public Health team is working closely with Tesco and colleagues in Public Health England.
"All staff affected are self-isolating in accordance with government guidance."