On August 11, 2021, in the context of the vaccine roll-out and emerging COVID-19 variants of concern, Ontario released COVID-19 Fully Immunized and Previously Positive Individuals:  Case, Contact and Outbreak Management Interim Guidance (Guidance), which provides updated recommendations for case, contact, and outbreak management of fully immunized and previously positive individuals in the province. 

The Guidance provides that individuals are:

• Fully immunized when 14 days or more have passed after they received their second dose of a two-dose vaccine or their first dose of a one-dose vaccine; and
• Previously positive when their positive result was 90 or more days ago and they have been cleared from their initial infection.

Symptomatic Individuals 

According to the new Guidance, although symptomatic individuals who are fully immunized or were previously positive must self-isolate and get tested immediately, they are not required to continue to self-isolate upon receiving a negative PCR test, provided they are afebrile (i.e., free from fever), and their symptoms have improved for at least 24 hours.  If they are experiencing gastrointestinal symptoms (e.g., nausea/vomiting, diarrhea, stomach pain), these symptoms need to be resolved for at least 48 hours.  Finally, if such individuals decline testing, they should remain in isolation for 10 days following their last exposure.

Household Members

Fully immunized and previously positive asymptomatic household members of a symptomatic person are not required to stay at home until the symptomatic individual tests negative. 

Individuals Who Test Positive

Fully immunized or previously positive individuals who test positive should self-isolate.  If they are symptomatic, they should be managed in accordance with the standard Management of Cases and Contacts of COVID-19 in Ontario guidance.  If they are asymptomatic, they should be re-tested as soon as possible and managed in accordance with section 4.6 of the Management of Cases and Contacts of COVID-19 in Ontario guidance as “low pre-test probability” positive. 

Individuals with High-Risk Exposures

For 10 days after their last exposure, fully immunized or previously positive individuals who have had high-risk exposures should wear a mask and maintain physical distancing when outside their home, self-monitor for symptoms daily, and self-isolate immediately if symptoms develop.  Such individuals are also encouraged to report their exposure to their employer and/or workplace Occupational Health Department, and to follow any work restrictions.    

Individuals Who Are Symptomatic

Symptomatic fully immunized or previously positive individuals who have a high-risk exposure are recommended to get tested as soon as possible and must self-isolate pending test results.  If their test result is negative, the individual is not required to continue self-isolation provided their symptoms are improving and they are afebrile for at least 24 hours.  If such individuals are experiencing gastrointestinal symptoms, they should be resolved for at least 48 hours.  Finally, if a symptomatic fully immunized or previously positive individual declines testing, they should remain in isolation for 10 days following their last exposure.

Individuals Who Are Asymptomatic

Asymptomatic fully immunized or previously positive individuals who have had a high-risk exposure should be tested in accordance with Provincial Testing Guidance; they do not, however, need to self-isolate while awaiting test results.  Self-isolation may still be required of fully immunized or previously positive asymptomatic individuals who have had a high-risk exposure at the discretion of the local public health unit (PHU). 

Residents of Long-term Care/Retirement Homes, Inpatients and Other Individuals with Increased Risk of Secondary Transmission

Self-isolation and testing of fully immunized or previously positive residents of long-term care/retirement homes, inpatients and other individuals with increased risk of secondary transmission who have had a high-risk exposure is recommended, even if they are asymptomatic. 

Healthcare Workers

Asymptomatic fully immunized or previously positive healthcare workers who have had a high-risk exposure are not required to self-isolate. They must, however, get tested as soon as possible, maintain masking and physical distancing outside of the home, and self-monitor for symptoms for 10 days from their last exposure.  They are encouraged to report their exposure to their employer and/or workplace Occupational Health Department and follow any work restriction requirements.  Finally, such individuals must self-isolate immediately and get tested if they develop symptoms of COVID-19. 

Individuals Who are Part of an Outbreak

Asymptomatic Point Prevalence Testing

In an outbreak setting, asymptomatic point prevalence testing (i.e., testing to define the scope of the outbreak) can exclude fully immunized and previously positive individuals, including healthcare workers, non-healthcare-workers, essential caregivers, residents of long-term care homes or retirement homes, and patients admitted to a hospital. 

Such individuals should be included, however, in point prevalence testing if a high-risk exposure is determined or cannot be ruled out; ongoing/uncontrolled transmission is occurring; there is an indication that symptomatic cases are occurring among fully vaccinated individuals; the outbreak is occurring in a particularly vulnerable population; or operationally, it is infeasible to distinguish such individuals in a timely way to be excluded from point prevalence testing.

It is recommended that asymptomatic fully immunized and previously positive individuals with a positive result from point prevalence testing be subjected to a repeat test as soon as possible.

If symptomatic cases are identified among fully immunized individuals, a more aggressive approach to contain the outbreak might be warranted, e.g., quarantining fully immunized individuals with high-risk exposures. 

Cohort Dismissals

In settings with cohort-based dismissals of potentially exposed individuals (e.g., schools/childcare, camps, some workplaces), cohorts should continue to be dismissed to facilitate timely exclusions of potentially exposed individuals from the setting.  Return of partial cohorts is permitted at the discretion of the PHU. 

Bottom Line for Employers

The purpose of the Guidance is to supplement or, where applicable, supersede the guidance in Management of Cases and Contacts of COVID-19 in Ontario with updated recommendations for case, contact, and outbreak management of fully immunized and previously positive individuals in Ontario.  Employers in Ontario are encouraged to become familiar with the Guidance, if for no other reason than to understand that the requirement to self-isolate will no longer apply to many employees. 

Employers should also be aware that the Guidance recommends that their fully immunized and previously positive employees continue to follow general public health guidance and recommended infection-control measures.