LONDON, ONT -- The Middlesex-London Health Unit (MLHU) has declared a COVID-19 outbreak at Piero's Pizza in south London, after four staff members tested positive for COVID-19.

Case Investigators determined that three of the staff members worked while they were infectious.

MLHU said it was first notified of the inital COVID-19 case at the business located at 169 Wharncliffe Road on Tuesday, January 19, with additional cases reported on Friday Jan. 22.

"After investigating these new cases, the Health Unit has determined that transmission of COVID-19 has likely occured at the store," said Dr. Alex Summers, associate medical officer of health.

Employees have indicated that they wore masks while at work and that there is a plexiglass barrier between customers and staff at the business, said MLHU.

The Heath unit is advising customers who visited Piero's or had pizza delivered between Jan. 15 and Jan. 19, to mintor themselves for symptoms and to get tested if those symptoms develop.