To date, 18 positive cases have been recorded in the Oswestry and Ellesmere areas either as workers at Cake Crew in Bala or household contacts.
Shropshire Council is working closely with public health colleagues in Gwynedd following cases of the virus.
A number of the staff at the Cake Crew factory live in Shropshire.
Rachel Robinson, Shropshire Council’s director of public health, said: “We have been made aware of 18 positive cases of Covid-19 in Shropshire linked to the outbreak at Cake Crew in Bala.
“We are working closely with health officials in Wales and with our local communities to help limit any further potential spread.
"All positive cases are self-isolating for at least 10 days, with contacts isolating for 10 days, as per national guidance.
“This underlines the importance of everyone taking regular lateral flow tests twice a week, particularly to help identify anyone who has the virus but does not have symptoms.”
Lateral flow test home kits are available in Oswestry at: The Victoria Centre, Oswestry Library, The Qube and Oswestry Leisure Centre and from Ellesmere Pharmacy in Scotland Street.