The health care provider who makes the diagnosis has the obligation to call and inform Public Health right away.
The Public Health official will conduct the investigation and contact the employer, notifying them about the investigation.
Any disclosure to other employees must respect privacy legislation and be done in accordance with advice from the public health unit.
Specific requirements vary by jurisdiction.  At a minimum, restrict access to area(s) the employee worked and comprehensively disinfect the premises using a Health Canada-approved disinfectant.
Continue to practice physical distancing, regular handwashing and other regularly prescribed COVID-19 mitigation protocols
Generally, an employer is not obligated to inform customers. Public Health officials will conduct an investigation and provide the required follow-up.
RCC has an incident checklist for retailers dealing with a positive COVID-19 case. View checklist.