Treatments and testing remain available for people at high risk of severe COVID-19

To: All Physicians
Category: Physician services; Primary health care services
Written by: Health Programs and Delivery Division
Date issued: September 18, 2023
Bulletin Number: 230906

As part of Ontario’s readiness plan for the fall respiratory season, the Ministry of Health is continuing to provide access to free COVID-19 antiviral treatments and testing for people at high-risk of severe illness from COVID-19.

Antiviral treatments for COVID-19

In Canada, oral nirmatrelvir/ritonavir (Paxlovid™) and intravenous remdesivir (Veklury™) are Health Canada approved treatments for outpatient use. Antiviral treatments should be strongly considered for individuals with mild to moderate COVID-19 symptoms, a positive test for SARS-CoV-2 (based on a positive PCR, rapid molecular, or rapid antigen test result), and who are at high risk of severe outcomes.

“High-risk” patients who may be considered for antiviral treatment include:

  • Adults 60 years of age and older, regardless of vaccination status, with no other risk factors
  • Adults 18 years of age and older who are immunocompromised, regardless of age, vaccine status, or prior infections.
    • active hematological malignancy or post stem cell transplant or CAR T-cell therapy in last 6 months
    • solid organ transplant
    • hypogammaglobulinemia
    • taking prednisone greater than 20 mg/day (or equivalent) for more than 14 days
    • other moderately or severely immunosuppressive therapies (example: anti-CD20 agents, alkylating agents, cancer chemotherapy)
  • Adults with one or more underlying conditions that puts them at high risk for severe COVID-19 outcomes
  • Adults with inadequate immunity, such as:
    • Unvaccinated or under-vaccinated (example: completed primary series AND last COVID-19 vaccine dose was more than 6 months ago AND last SARS-CoV-2 infection was more than 6 months ago).
    • See the most recent immunization guidance from National Advisory Committee on Immunization to determine if your patient is under-vaccinated.

Eligibility is based on clinical judgement. A patient may be at high risk of severe COVID-19 but, based on a clinical assessment (and pharmacy consultation), a physician may determine that COVID-19 antiviral treatment is not appropriate.

While not routinely recommend in children less than18 years of age, antivirals may be considered in exceptional circumstances (example: severe immunocompromise and/or multiple risk factors, clinical profession) on a case-by-case basis. Multidisciplinary consultation with Infectious Diseases (or Pediatric Infectious Diseases) and the team primarily responsible for the child's care is recommended.

Please note, vaccination continues to be the best way for people to stay healthy and prevent unnecessary visits to the hospital.

For more information on accessing antiviral treatments for COVID-19 in the community, see Ontario Health’s document.


Nirmatrelvir-ritonavir (Paxlovid™) is the preferred first-line antiviral treatment for patients within five days of symptom onset where safe and feasible. Nirmatrelvir/ritonavir (Paxlovid™) can be prescribed by physicians, nurse practitioners, and pharmacists, and can be dispensed at community pharmacy locations.

Consultation with a pharmacist may be helpful to mitigate any significant drug-drug interactions (including natural products).  To guide appropriate prescribing, please see the guidance document “Nirmatrelvir/ritonavir (Paxlovid™): What prescribers and pharmacists need to know” for more information.


Remdesivir (Veklury™) is administered as an IV infusion on three consecutive days for non-hospitalized patients. The first dose should be administered within seven days of symptom onset.

Remdesivir is indicated where nirmatrelvir/ritonavir is contraindicated (example: drug-drug interaction that cannot be safely managed, medical contraindication) or when patients are beyond the treatment window for nirmatrelvir/ritonavir initiation (such as symptom onset greater than five days).

Remdesivir (Veklury™) can be prescribed by physicians and nurse practitioners. Prescribers in hospitals or in the community can refer a patient to their local Home and Community Care Support Services (HCCSS) branch for a nurse to administer remdesivir infusions. Prescribers must complete a referral/prescription form along with the IV referral form and submit them to their local (HCCSS) branch. A (HCCSS) care coordinator will follow up with the patient.

To guide appropriate prescribing, please see this guidance document from Ontario Health: Recommendations for Outpatient Use of Intravenous Remdesivir (Veklury) in Adults. 

Assessing patients in advance

Where possible, physicians are encouraged to prioritize assessments for patients who may be eligible for antivirals, given the timing constraints on administering treatment. This includes pre-assessing high-risk patients for eligibility for antivirals in advance of a positive COVID-19 test or symptoms.


To initiate treatment, patients must have tested positive for COVID-19. A rapid antigen test (self-administered or provider-administered), a PCR test, or a rapid molecular test are all acceptable testing options. Note that a negative rapid antigen test does not rule out the possibility of a COVID-19 diagnosis.

Patients at high risk of severe outcomes of COVID-19 are eligible for PCR or rapid molecular testing at provincial testing locations (including participating pharmacies, hospitals, assessment centres, and select primary care settings). Authorized providers may order publicly-funded PCR testing for eligible patients using the Public Health Ontario COVID-19 and Respiratory Virus Test Requisition form For help filling out the form use these instructions.

As of July 1, 2023, the public can access rapid antigen tests (RATs) through their local Public Health Units (PHUs). Additionally, RATs continue to be available to those in congregate care settings (such as Long-Term Care Homes), the broader public sector (such as education), First Nations & Indigenous Communities and High Priority Communities.

Rapid antigen tests (RATs) for patients

As previously communicated, health sector partners (including physicians, pharmacies, hospitals, and other healthcare providers) will be able to order RATs for distribution to their patients in preparation for the Fall/Winter respiratory season as of September 2023. The distribution of RATs to patients is voluntary and will not be reimbursable by the Government of Ontario (no billing codes).

The ordering pathway for health care providers already enrolled in the Provincial Antigen Screening Program (PASP) who intend to distribute RATs to employees and/or patients will continue through the PPE Supply Portal. Healthcare providers that are not currently enrolled in PASP can enroll in the program via the Ontario Together Portal and order through the PPE Supply Portal. For assistance in creating an account or accessing an existing account, or for any questions about orders and shipment, please contact

Resources for providers and patients

Ontario Health has developed recommendations and resources for health care providers on the use of COVID-19 antiviral treatments. Please visit Ontario Health’s website to review these recommendations and resources. Ontario Health has also created a Paxlovid handout for patients available in 29 languages that can be shared with patients.

For more information, please visit the Ministry of Health’s COVID-19 Antiviral Treatments webpage. Patients can access Ontario’s antiviral screener tool to help determine if they are at high risk and should be assessed for antiviral treatment.

The Centre for Effective Practice also maintains a resource page on outpatient management of COVID-19.

CanTreatCOVID Study

The CanTreatCOVID Study is open to adults in Ontario aged 18 – 49 years with one or more chronic condition(s), or adults aged 50 years and over who have tested positive for COVID-19 with symptoms starting within the last five days. Participants in the study may be eligible to receive COVID-19 medications (including Paxlovid™). Patients can visit the CanTreatCOVID webpage or call 1-888-888-3308 to participate.

Other information on post COVID-19 condition

For resources on post COVID-19 condition (PCC), also known as long COVID, Ontario Health has developed clinical guidance to help primary care providers assess, manage, and refer patients who may have long COVID. The ministry has launched a long COVID diagnostic code to provide data on the condition and improve the healthcare services provided to individuals with PCC. The Centre for Effective Practice also maintains a resource page on long COVID with the latest evidence.


COVID-19 antiviral treatment; Paxlovid; nirmatrelvir/ritonavir; remdesivir; Veklury; COVID-19

Contact Information

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