Sentinel Practitioner Surveillance Network (SPSN) — Influenza Vaccine Effectiveness Program

Respiratory virus surveillance is important for controlling the spread of influenza, SARS-CoV-2 and other respiratory viruses in Ontario. The Sentinel Practitioner Surveillance Network (SPSN) supports provincial, national and international respiratory pathogen surveillance and assesses the effectiveness of the influenza and COVID-19 vaccines annually.


The goal of the SPSN is to evaluate the effectiveness of the influenza and COVID-19 vaccines each year. The SPSN relies on a network of primary care practitioners in each participating province (British Columbia, Alberta, Ontario and Quebec) to collect and submit respiratory specimens for testing and analysis. Ontario has been part of the SPSN since 2008.

How it Works

Participation in the program is voluntary. Sentinels can sign up annually to be a part of the SPSN. Throughout the year, particularly during respiratory illness periods, sentinels are required to submit one to two respiratory specimens (e.g. nasopharyngeal swab) per week from patients presenting with acute respiratory illness (ARI) or influenza-like Illness (ILI). In light of the COVID-19 pandemic, the surveillance of SARS-CoV-2 was overlaid upon the existing system and practice of the SPSN for influenza and other respiratory pathogens.

Participation requires the completion of a short questionnaire on the SPSN specific test requisition where sentinels are asked to briefly detail the patient’s influenza and COVID-19 vaccine history. Specimens are then sent to Public Health Ontario’s (PHO) laboratory where they are tested for influenza and other respiratory viruses as part of the surveillance program.

Information generated by the SPSN is used to help inform public health policies regarding vaccinations, and ongoing prevention and control efforts relating to respiratory pathogens across Ontario and Canada. Additionally, the SPSN contributes to the scientific knowledge base through peer-reviewed journal articles, presentations at academic conferences, as well as assists the World Health Organization (WHO) in their vaccine strain selection process.

Recruitment for the program is conducted in collaboration with the College of Family Physicians of Canada National Research System along with SPSN outreach activities.

Ethics Review

All SPSN program activities in Ontario and Alberta have been granted research ethics board approval while the program is considered regular public health surveillance in British Columbia and Quebec.

Why Participate?

We rely on sentinels to help us monitor respiratory pathogen activity across Ontario and evaluate the performance of the seasonal influenza and COVID-19 vaccines.

Your participation also contributes towards:

  • Informing provincial and national vaccination strategies and the World Health Organization’s (WHO) recommendations for the seasonal influenza vaccine composition in the northern hemisphere
  • Data-driven patient care with timely results regarding your patient’s diagnosis
  • Bringing valuable knowledge to your practice with a better grasp of respiratory pathogen activity in the community

Who Can Participate?

Sentinels (primary care practitioners including family physicians and nurses in the extended class/nurse practitioners) can sign up annually to be a part of the SPSN.

How to Participate?

Fill out a Consent Form and email the completed form to OR fax completed form to (416) 235-6103, Attn: SPSN program.

Requirements for Participation


Fill out a Sentinel Consent Form and send the completed form to or fax to (416) 235-6103, Attn: SPSN program.


Following receipt of your consent form, you will receive an information package with instructions and a set of respiratory test kits from PHO’s laboratory - Sentinel Practitioner Surveillance Network (SPSN).


Using the swabs provided by the SPSN, collect a nasopharyngeal (preferred) or nasal swab from patients presenting to the clinic with influenza-like illness (ILI)* or acute respiratory illness (ARI)** within seven days of onset.

Specimen collection can commence as soon as you receive your collection kits and continue until the end of the current respiratory illness period or until notified by the SPSN coordinator.


Submit a minimum of one to two specimens per week (20-25 in total) from eligible patients during the study period to PHO’s laboratory. The laboratory will test the respiratory specimens sent for diagnosis as part of this study and send you the results within 7 days. ***


Ensure that each specimen is appropriately labeled and submitted with a completed requisition including the SPSN questionnaire. This not only allows for efficient testing and reporting but also provides a comprehensive data set to calculate vaccine effectiveness.

* ILI definition: acute onset of respiratory illness with fever and cough and one or more of the following: sore throat, arthralgia, myalgia or prostration, which could be due to influenza virus.

** ARI definition: acute onset of respiratory illness with new or worsening cough.

*** We encourage sentinels to register to PHO’s AutoFax service for a timely report of lab results. Please contact PHO’s Customer Service Centre at (416) 235 - 6556 or 1-877-604-4567 (toll free) to register.


At the end of the season, you will be compensated $20 per specimen sent to the laboratory with a completed short questionnaire.

This page contains information for sentinels on collecting specimens, completing the requisition form, transporting specimens and reporting results. See the Instruction Sheet for full details.

Collecting Specimens

  • Wear appropriate Personal Protective Equipment to protect yourself.
  • Ask patients who have copious discharge or mucus to gently clean their nose with a tissue.
  • Collect an appropriate nasopharyngeal (preferred) or nasal specimen.
  • Place the swab into the accompanying vial of universal transport medium. Break the swab at its break point so the swab stays in the vial. Tighten the lid securely.
  • Label the vial with the patient’s full name and date of birth. Place the specimen in the biohazard bag provided and seal the specimen pocket of the bag using the adhesive strip.
  • Refrigerate at 4°C until transported to the lab.

Completing the Requisition Form

Complete all fields of the SPSN – Vaccine Effectiveness Test Requisition Form provided:

  • Fill out one separate form for each submitted specimen.
  • Under clinician/referring laboratory, enter the full name and billing address of the practitioner/facility to which the final report will be sent.
  • Enter the specimen collection date in the appropriate box.
  • Complete the questionnaire to help assess vaccine effectiveness in protecting against laboratory-confirmed influenza/COVID-19.
  • For each specimen, place the completed form in the outside pocket of each biohazard bag.
  • Use one biohazard bag for each specimen and the accompanying completed requisition form.

Transporting Specimens

  • Submit SPSN specimens to PHO’s laboratory via your usual lab submission route.

Reporting Results

Results will be reported directly to the submitter’s office. You will receive results from the Laboratory Information System using the AutoFax system. To register for AutoFax, call PHO’s Customer Service Centre at 416-235-6556 or 1-877-604-4567.

Current Publication List

  1. Skowronski DM, Chuang ESY, Sabaiduc S, Kaweski SE, Kim S, Dickinson JA, Olsha R, Gubbay JB, Zelyas N, Charest H, Bastien N, Jassem AN, De Serres G. Vaccine effectiveness estimates from an early-season influenza A(H3N2) epidemic, including unique genetic diversity with reassortment, Canada, 2022/23. Euro Surveill. 2023;28(5):pii=2300043.


  2. Shinhye, KChuang ESY, Sabaiduc SOlsha RKaweski SEZelyas NGubbay JBJassem ANCharest HDe Serres GDickinson JASkowronski DM. Influenza vaccine effectiveness against A(H3N2) during the delayed 2021/22 epidemic in Canada. Euro Surveill. 2022;27(38):pii=2200720.


  3. Skowronski DMZou MSabaiduc SMurti MOlsha RDickinson JAGubbay JBCroxen MACharest HJassem AKrajden MBastien NLi YDe Serres G. Interim estimates of 2019/20 vaccine effectiveness during early-season co-circulation of influenza A and B viruses, Canada, February 2020. Euro Surveill. 2020;25(7):pii=2000103.


  4. Skowronski DM, Zou M, Clarke Q, Chambers C, Dickinson JA, Sabaiduc S, Olsha R, Gubbay JB, Drews SJ, Charest H, Winter AL, Jassem A, Murti M, Krajden M, De Serres G, Influenza Vaccine Does Not Increase the Risk of Coronavirus or Other Noninfluenza Respiratory Viruses: Retrospective Analysis From Canada, 2010–2011 to 2016–2017, Clinical Infectious Diseases, Volume 71, Issue 16, 15 October 2020, Pages 2285–2288,


  5. Skowronski DM, Leir S, Sabaiduc S, Chambers C, Zou M, Rose C, Olsha R, Dickinson JA, Winter AL, Jassem A, Gubbay JB, Drews SJ, Charest H, Chan T, Hickman R, Bastien N, Li Y, Krajden M, De Serres G, Influenza Vaccine Effectiveness by A(H3N2) Phylogenetic Subcluster and Prior Vaccination History: 2016–2017 and 2017–2018 Epidemics in Canada, The Journal of Infectious Diseases, Volume 225, Issue 8, 15 April 2022, Pages 1387–1398,


  6. Skowronski DMSabaiduc SLeir SRose CZou MMurti MDickinson JAOlsha RGubbay JBCroxen MACharest HBastien NLi YJassem AKrajden MDe Serres G. Paradoxical clade- and age-specific vaccine effectiveness during the 2018/19 influenza A(H3N2) epidemic in Canada: potential imprint-regulated effect of vaccine (I-REV). Euro Surveill. 2019;24(46):pii=1900585.


  7. Skowronski DMLeir SSabaiduc SMurti MDickinson JAOlsha RGubbay JBCroxen MACharest HChan TBastien NLi YKrajden MDe Serres G. Interim estimates of 2018/19 vaccine effectiveness against influenza A(H1N1)pdm09, Canada, January 2019. Euro Surveill. 2019;24(4):pii=1900055.


  8. Skowronski DMChambers CDe Serres GDickinson JAWinter ALHickman RChan TJassem ANDrews SJCharest HGubbay JBBastien NLi YKrajden M. Early season co-circulation of influenza A(H3N2) and B(Yamagata): interim estimates of 2017/18 vaccine effectiveness, Canada, January 2018. Euro Surveill. 2018;23(5):pii=18-00035.


  9. Skowronski DMChambers CSabaiduc SDickinson JAWinter ALDe Serres GDrews SJJassem AGubbay JBCharest HBalshaw RBastien NLi YKrajden M. Interim estimates of 2016/17 vaccine effectiveness against influenza A(H3N2), Canada, January 2017. Euro Surveill. 2017;22(6):pii=30460.


  10. Skowronski DMSabaiduc SChambers CEshaghi AGubbay JBKrajden MDrews SJ, Martineau C, De Serres G, Dickinson JA, Winter A-L, Bastien N, Li Y. Mutations acquired during cell culture isolation may affect antigenic characterisation of influenza A(H3N2) clade 3C.2a viruses. Euro Surveill. 2016;21(3):pii=30112.

Current Influenza Season Updates

Canada had an earlier start to the influenza season with influenza activity increasing greatly in October 2022 and peaking in December 2022 (WHO, Influenza Update 436, 09 Jan 2023). During the peak, subtyped viruses predominantly involved influenza A(H3N2). As of February 2023, the proportion of both influenza A(H1N1) and influenza B detections has slightly increased, but remains low. For the 2022-23 season, 98% of antigenically characterized A/H3 viruses were characterized as antigenically similar to A/Darwin/6/2021 (H3N2)-like virus with antisera raised against cell-grown A/Darwin/6/2021 (H3N2)-like virus. A/Darwin/6/2021 (H3N2)-like virus is an influenza A/H3N2 component of the 2022-23 Northern Hemisphere influenza vaccine. (FluWatch Surveillance, Weekly influenza report)

The 2022-23 northern hemisphere influenza vaccines contain the following influenza strains:

  1. A/Victoria/2570/2019 (H1N1)pdm09-like virus
  2. A/Darwin/9/2021 (H3N2)-like virus and
  3. B/Austria/1359417/2021-like virus (Victoria lineage)
  4. B/Phuket/3073/2013-like virus (Yamagata lineage; in quadrivalent vaccines only)

For Ontario-specific updates, check out the Ontario Respiratory Pathogen Bulletin.

Ontario Respiratory Pathogen Bulletin

The Ontario Respiratory Pathogen Bulletin is a comprehensive weekly summary of respiratory pathogen activity in the province.

How many respiratory specimens should be collected by each sentinel practitioner?

This may vary, however based on statistical power calculations and experience from several influenza seasons, it is anticipated that a minimum of one to two specimens per week may be submitted by each sentinel practitioner over the course of the SPSN surveillance period for a total of 20-25 specimens per season. In the national collaboration between British Columbia, Alberta, Ontario and Quebec, we are aiming for a total of 3,000 respiratory specimens as part of this study.

When should I start collecting specimens from patients presenting with symptoms of influenza-like illness (ILI) or acute respiratory illness (ARI) this year? When do I stop?

You can start submitting specimens as soon as you receive the information package and testing kits. Please continue to submit samples until notified by the SPSN coordinator.

Which patients are eligible for inclusion?

Any patient who is a resident of Ontario, who presents in your practice with symptoms of an influenza-like illness (ILI) or acute respiratory illness (ARI) within one week of ILI symptom onset.

You should collect a nasopharyngeal or nasal swab using the test kits provided by the SPSN for testing. You will be notified if specimen collection for the purpose of the SPSN will change. Please note that it is important that you collect respiratory specimens from patients who are residents of participating provinces (British Columbia, Alberta, Ontario and Quebec) and who are presenting within seven days of ILI onset, whether or not they received the influenza vaccine.

Should I submit SPSN specimens to the laboratory where I usually send respiratory specimens?

Yes. Sentinels can submit SPSN specimens to PHO’s laboratory via their routine lab submission process. Specimens will be directed to PHO by your laboratory. Please ensure that a fully completed SPSN requisition is submitted with each specimen.

Will I be compensated for my time?

Yes. As your time, effort and participation are much appreciated, participating sentinels will be compensated $20 for each specimen submitted with a completed SPSN-specific requisition. Reimbursement will be made at the end of each period.

Has this study received ethics approval and if so, what special ethics requirements are there?

The SPSN’s methodology has been reviewed by ethics boards in each participating province every year since 2004. In more recent year separate ethics review and approval has been granted in Alberta, and Ontario while SPSN activities in British Columbia and Quebec are considered regular public health surveillance. For the 2022-2023 season, ethics approval for SPSN Ontario was granted in the fall of 2022. As part of the program, sentinel physicians and nurse practitioners are required to inform their eligible patients and elicit verbal consent to participate through specimen collection and questionnaire completion. A verbal consent script has been drafted by SPSN investigators for this purpose and is included with the study material sent to consenting sentinels

Who else is involved in this study?

In each participating province (ON, BC, AB, QC), a team of epidemiologists and laboratory investigators has been established. These investigators have been working collaboratively for several years and Ontario investigators and sentinels will again join that team of provincial investigators this season.

How will vaccine effectiveness be calculated?

Vaccine effectiveness  against laboratory confirmed influenza and COVID-19 infection is calculated by SPSN researchers based on a case control design. Using the laboratory results (either positive or negative for influenza & COVID-19) and the answers to the questions accompanying the laboratory requisition (e.g., recent immunization history), vaccine status is compared for those with and without influenza & COVID-19. The program is based on the understanding that not everyone with ILI will have influenza. Those who test positive for influenza are counted as cases, whereas those who test negative for influenza become the controls. Immunization rates among these two groups are used for VE estimation.

Where will this analysis be done nationally and how will confidentiality be preserved?

Since 2004, an overall vaccine effectiveness result has been calculated for all participating provinces combined nationally through statistical analysis at the British Columbia Centre for Disease Control (BCCDC).

Data from Quebec, Ontario, and Alberta that are shared with BCCDC do not include any personal identifiers and chronic medical conditions, as specified by ethics boards. Absolutely no personal identifying information will be transmitted. Only the influenza test result and relevant epidemiologic information provided on the requisition are shared for the sole purpose of calculating an aggregate vaccine effectiveness result. At each level, all data is stored in a secure and locked facility. Dr. Danuta Skowronski, principal investigator, is located at the BCCDC.

Do I need special equipment for the study?

You will need:

  • Test kits (provided by PHO’s laboratory – Toronto location PHO’s laboratory, Toronto location).
  • A fridge to store specimens at 4°C until transported to lab. Specimens should be shipped as soon as they are collected, but this is not always possible.

How do I receive results for specimens I submitted?

In order to reduce the turnaround time and increase the efficiency of testing and reporting, results will be reported automatically by the Laboratory Information System using the AutoFax system. To register for AutoFax, please contact the Toronto Public Health Laboratory’s Customer Service Centre at 416-235-6556 or 1-877-604-4567.

Where can I get more information about what else is circulating in my area?

Please refer to the Ontario Respiratory Pathogen Bulletin for more information.

How can I contact the SPSN team?

By email:
By phone: (647) 792-3187
By mail
Sentinel Practitioner Surveillance Network
Public Health Ontario 661 University Avenue, Suite 1701
Toronto, ON M5G 1M1

If you are interested in the SPSN, sentinel consent forms can be submitted by email to or faxed to (416) 235-6103.

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Updated 22 Nov 2019