Confused about COVID? Family doctors answer your questions (University of Toronto & College of Family Physicians of Ontario)

I’m not feeling well. How do I know if I have COVID? What should I do? (Confused about COVID?)

A positive rapid antigen test (RAT) is now considered diagnostic of COVID in the current situation where case numbers in the community are high. A PCR swab is not needed to confirm. Note that this accuracy will change as the community prevalence reduces. At low community case numbers (low “pre test probability”) the proportion of positive RATs that are false positives increases, reducing the usefulness.

RATs are less sensitive for the Omicron variant compared to the Delta variant using a nasal sample only, particularly in the first 2 days after infection. The ability to detect Omicron is improved by using a new oral-nasal sample collection technique (using the same swab). See instructions for collection below.

A single negative RAT does not reliably rule out infection. Two negative RATs separated by a minimum of 24-48 hours apart are considered to rule out COVID diagnosis. Symptomatic patients should still isolate until improving as per the current isolation recommendations.

How to use RATs for Asymptomatic Screening

RATs are being used in some work or other settings (including primary care clinics) to reduce transmission of cases by regular screening of asymptomatic individuals. Because there is a delay between infection and development of a positive RAT (see the graph on the left), frequent screening is key to effective use. The graph on the right shows the reason for the current recommendation that testing be done between 3 and 5 times per week when using for screening.

Sensitivity of RAT in detecting COVID infection
(days since positive PCR)
Reduction in COVID cases with different frequencies of asymptomatic screening using RATs

Modified from Ontario Science Table: Use of Rapid Antigen Tests During the Omicron Wave

Collection Techniques for adults and children

To improve the ability to detect the Omicron variant, the recommended swab technique for RATs is now an oral-nasal sample collected using the same swab. Individuals can collect these samples by initially swabbing the inside of both cheeks, followed by the back of the tongue or throat, and then both nostrils.

Video instructions from Ontario Science Table: Use of Rapid Antigen Tests During the Omicron Wave

Video instructions for adults

Video instructions for children

Written instructions from Public Health Ontario: COVID-19 Rapid Antigen Tests: How to Collect a Sample

Read more detail here: 

Ontario Science Table: Use of RATs During the Omicron Wave

Otherwise healthy adults and children can self-isolate, and will not need to seek medical care. If you have symptoms, you can find detailed advice from Hamilton Family Medicine on COVID-19 below.

Connect with your family doctor if you are in a higher-risk group* and have symptoms; your COVID symptoms get worse; or you are experiencing moderate to severe illness.

If you are at a higher risk of more serious illness* you may benefit from closer regular monitoring from your family doctor, which may include check-in calls and in some cases loan of a pulse oximeter to use. (A pulse oximeter is a small clip that measures how much oxygen your blood is carrying.) You may also be eligible for treatments. 

COVID-19 antiviral treatment screener

Antiviral treatments are now available in the community (outside of a hospital) for people with symptoms (even if mild) who are at higher risk of severe COVID-19. These treatments must be taken within the first 5 to 7 days of your symptoms starting.

Take this screener to determine if you are at higher risk of severe COVID-19 and may benefit from these treatments.

Antiviral treatment patient handout

*Higher risk group: If you have symptoms and are: over 60 OR have any long-term medical conditions OR are unvaccinated OR are pregnant you should contact your usual primary care clinic for an assessment of whether closer monitoring is required and information about managing your illness.  Contact your family doctor early in your illness rather than waiting for symptoms to worsen.

COVID-19 Guides for Patients

This applies to test positive (PCR, rapid molecular, or rapid antigen) or clinical symptom diagnostic algorithm positive.

Changes to ministry guidance include elimination of minimum isolation periods for most cases. Here’s a summary of current guidance:

  • Individuals who have symptoms of ANY respiratory illness should stay home until symptoms have been improving for at least 24 hours (48 hours if nausea, vomiting or diarrhea)
  • If they have a fever, they should stay home until the fever is completely gone.
  • Avoid non-essential visits to vulnerable people for a full 10 days starting the day after symptoms appear.
  • Symptomatic and test-positive individuals should wear a mask when in public spaces for 10 days from the start of symptoms/positive test result
  • For those who are hospitalized, immunocompromised or reside in a highest-risk setting (i.e., acute care, long-term care and retirement homes, group homes, shelters, etc.), 10-day isolation remains and symptoms must be improving as noted above. Note: does not include primary care (see points above which apply to Primary Care, and page 7 of Guidance).

For healthcare workers in highest-risk settings referenced above:

  • Close contacts of someone with a positive COVID test or symptoms may work in their highest-risk work setting if asymptomatic.
  • No change to isolation requirements for symptomatic or test positive individuals who work in highest-risk settings – may return to work 10 days after onset of symptoms or positive test result. Testing for clearance is generally not recommended. See Appendix A of Guidance for more, including options for critical staffing shortages and workplace measures for reducing risk.

  • Information on where to get vaccinated in Hamilton and answers to frequently asked COVID-19 vaccines questions is available on City of Hamilton website



  • Sleep Well (prepared by Martha Bauer, Colleen O’Neill, Kiska Colwill and Naomi Dore)