Influenza occurs globally with an annual attack rate estimated at 5 – 10 per cent in adults and 20 – 30 per cent in children. In Canada, influenza generally occurs each year in the late fall or winter months.

The tabs below offer health professionals key information about influenza vaccination, infection prevention and control, diagnosis, and treatment of seasonal influenza.


  • Sudden onset of high fever, chills, cough and muscle aches
  • Other common symptoms include:
    • Headache
    • Chills
    • Loss of appetite
    • Fatigue
    • Sore throat
  • Nausea, vomiting and diarrhea may also occur, especially in children.

For local, provincial and national influenza surveillance information:

  • Obtain laboratory testing (nasopharyngeal swab collected in a respiratory virus collection kit) in all persons with suspected influenza who require hospital admission.
  • Influenza testing is not currently available through the Public Health Ontario Laboratory for patients in ambulatory settings, including those at high risk for influenza complications or patients in emergency department settings who will not be admitted to hospital. Current clinical guidelines recommend, during influenza season, that influenza antiviral therapy (e.g., oseltamivir or zanamivir) be started empirically for patients with severe acute respiratory illness (e.g., requiring hospitalization), or at high risk of influenza complications/severe disease. Therapy should not be delayed while awaiting test results. 

More information: PHO’s Labstract: Respiratory Viral Testing Algorithm – Update for Fall and Winter 2017-2018

In response to the increased influenza B activity, please give QIV to all unvaccinated individuals, including adults over 18 years of age. This may be particularly important for adults 65 years of age and older, especially those living in a facility.

There is no evidence to support re-vaccination for those who have already received TIV.

2017-2018 Influenza quadrivalent inactivated vaccines (QIV) strains:

  • A/Michigan/45/2015 (H1N1)
  • A/Hong Kong/4801/2014 (H3N2)
  • B/Brisbane/60/2008
  • B/Phuket/3073/2013

Order QIV injectable vaccine from OGPMSS, for all adults and children in your practice.

For more information, refer to the Canadian Immunization Guide, Seasonal Influenza Vaccine for 2017-2018.

When caring for people with influenza or influenza-like illness, follow Provincial Infectious Diseases Advisory Committee’s Routine Practices and Additional Precautions in all Health Care Settings including:

  • Droplet and contact precautions
  • Facial protection (which may include a mask in conjunction with eye protection, or a face shield that covers eyes, nose and mouth) within two metres of a patient on droplet precautions
  • Isolation in a single room or cohorted with another lab-confirmed case
  • Continued precautions for five days after onset of illness.

In addition, advise patients with influenza-like illness to stay home from work or school while ill, and to practise frequent hand washing and cough etiquette.

  • Influenza cases and respiratory infection outbreaks in institutions are both reportable to local public health.
  • Report confirmed cases of influenza to TPH.
  • Healthcare facilities must continue to report respiratory outbreak to TPH.
  • To report call 416-392-7411 during business hours and 3-1-1 on evenings and weekends.