Before the pandemic, the term contact tracing was rarely mentioned or dealt with in most workplaces. A public health unit (PHU) performs contact tracing investigations to determine the source of virus transmission(s) after an individual has tested positive for COVID-19. The PHU will collect information about potential contacts and follow up with them directly. Public Health Unit activities are covered under their relevant legislative framework.
When public health is doing contact tracing, they are trying to find out who may have been exposed to an infected person (a case). To do this, these healthcare workers will interview the infected person to identify places that they have visited while they were infectious. Next, they try to identify people with whom they have been in contact. The goal is to stop the pandemic spread. The information collected is medical information with a reasonable expectation of privacy.
This makes sense, especially when one considers the stigma of becoming COVID-19 positive.
The success of any contact tracing investigation will depend on careful planning, consideration of local contexts, and most importalty, timely and accurate information. Since the onset of the COVID-19 pandemic, employers have been asked to maintain accurate information about cohorts, shifts, work teams, service recipients and visitors logs to assist the public health units in their investigations.
The employer also has the responsibility under occupational health and safety legislation to investigate exposures in the workplace to prevent occupational illness spread. There is a separate fact sheet about this subject that can be found here:
 WHO: Contact tracing in the context of COVID-19; May 10, 2020;pg. 1 https://www.who.int/publications/i/item/contact-tracing-in-the-context-of-covid-19
 Ibid, pg. 1