Influenza (Flu)

What is the flu?

Seasonal influenza, also known as “the flu,” is a common, highly contagious respiratory infection that’s caused primarily by Influenza A and Influenza B viruses. The flu typically circulates in Ontario in the fall and winter.

Symptoms – which can include fever, chills, cough, muscle/body aches, a sore throat, and extreme tiredness – usually appear one to four days after a person has acquired the virus. Most people will recover within seven to 10 days. Symptoms like nausea, vomiting, and diarrhea are more common in children.


Signs and Symptoms of the flu

Flu symptoms can be similar to symptoms of COVID-19. Common symptoms of influenza can include;

  • fever
  • cough
  • muscle aches and pain
  • headache
  • chills
  • fatigue (tiredness)
  • loss of appetite
  • sore throat
  • runny or stuffy nose


While anyone can get the flu, individuals in the following groups are considered to be at high risk of severe complications:

  • Children six to 59 months (five years) of age;
  • Adults 65 years of age and older;
  • All pregnant individuals;
  • Residents of long-term care and chronic care facilities;
  • Indigenous peoples; and
  • Adults and children with the following chronic health conditions:
    • cardiac or pulmonary disorders (including bronchopulmonary dysplasia, cystic fibrosis, and asthma);
    • diabetes mellitus and other metabolic diseases;
    • cancer, immune compromising conditions (due to underlying disease, therapy, or both, such as solid organ transplant or hematopoietic stem cell transplant recipients);
    • renal disease;
    • anemia or hemoglobinopathy;
    • neurologic or neurodevelopment conditions (includes neuromuscular, neurovascular, neurodegenerative, neurodevelopmental conditions, and seizure disorders [and, for children, includes febrile seizures and isolated developmental delay], but excludes migraines and psychiatric conditions without neurological conditions);
    • morbid obesity (BMI of 40 and over); and
    • children six months to 18 years of age undergoing treatment for long periods with acetylsalicylic acid, because of the potential increase of Reye’s syndrome associated with influenza.


How is the flu spread?

Individuals with the flu can spread the virus when they cough, sneeze or talk. Droplets from an infected person can land in the mouth or nose of others who are nearby or can be inhaled into a person’s lungs. People can also get the flu by touching a surface that has the flu virus on it or by shaking hands with someone who has the flu and then touching their own eyes, mouth, or nose.


How can people protect themselves from coming down with the flu?

The influenza vaccine is the most effective way to prevent influenza illness and influenza-related complications.

Flu vaccines are free, and safe – including for kids and pregnant individuals – well-tolerated and are available via primary care providers, participating pharmacies, and Grey Bruce Health Unit clinics.

While the National Advisory Committee on Immunization strongly recommends that individuals get vaccinated before the onset of the flu season, the influenza vaccine can be administered until the end of the season.

The bottom line is, the sooner someone can get vaccinated within the flu season, the better.

Other ways to avoid getting and spreading the flu virus include: washing your hands often with soap and water, using a hand sanitizer with at least 70 percent alcohol content when soap and water are not available, covering your mouth when coughing or sneezing, not touching your face, staying at home when sick, and cleaning and disinfecting surfaces and shared items.


Information on Vaccination

Who should get the flu vaccine?

Individuals six months of age and older who do not have contraindications to the vaccine should get the influenza vaccine each year.

Vaccination is required each year because the contents of flu vaccines can vary from year to year. The World Health Organization reviews the specific strains in flu vaccines annually and can change them to provide a better match against the strains that the organization expects to see circulating in that given year. In addition, a person’s immune response to the flu vaccine may not continue beyond a year.



Can individuals get the flu vaccine and the COVID-19 vaccine at the same time?

For people aged five and up, yes!

The National Advisory Committee on Immunization recommends that for individuals five years of age and older, COVID-19 vaccines may be given simultaneously with, or at any time before or after, the influenza vaccine.

However, at this time, it is recommended that children aged six months to five years wait at least 14 days between a COVID-19 vaccination and a non-COVID-19 vaccine.


Can the flu vaccine also protect me against avian flu?

It’s particularly important for people who may have exposure to sick birds to get a seasonal flu vaccine, ideally two weeks before their potential exposure, if possible.

Seasonal flu vaccination will not prevent infection from bird flu viruses, but it can reduce the risk of getting sick with human and bird flu viruses at the same time.



Additional Information on influenza vaccination

The Grey Bruce Health Unit has developed several resources to help answer your questions about influenza and the flu vaccine.

This includes an Influenza Immunization Question & Answers document and infographics on Vaccine Safety and Influenza Prevention in Seniors.

You can also find more information about the flu on the Ministry of Health’s “The flu” webpage and Public Health Ontario’s Influenza webpage.


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