Influenza (the Flu)

Flu symptoms vary from person-to-person. Some people may only get mildly ill, while others very sick. Flu symptoms appear 1 to 4 days after exposure to the virus.

Classic flu symptoms include the sudden onset of:

• fever
• cough
• muscle aches and pains

Other common symptoms include:

• headache
• chills
• loss of appetite
• fatigue (tiredness)
• sore throat
• runny or stuffy nose

Children may also experience:

• nausea and vomiting
• diarrhea

Additional symptoms to watch for in children include:

• not drinking or eating as much as usual
• not waking up or interacting with others
• not wanting to play or be held (irritable)

Most people recover from the flu in 7 to 10 days with just supportive management.

Everyone is at risk of catching the flu.

Possible complications of the flu include:

• pneumonia and respiratory failure
• secondary bacterial infections
• worsening of chronic health conditions

Other severe outcomes of the flu:

• hospitalization
• death

The people at greatest risk of flu-related complications are:

• adults and children with the following chronic health conditions:
  • heart disease (e.g., congenital heart disease)
  • lung disorders (e.g., asthma, emphysema)
  • diabetes and other metabolic diseases
  • cancer or conditions resulting in a weakened immune system (due to the disease, therapy, or both)
  • kidney disease
  • anemia or blood disorders
  • nervous system disorders or neurodevelopmental conditions
  • morbid obesity
  • children 6 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 the flu)
• people of any age who are residents of nursing homes and other chronic care facilities
• adults 65 years of age and older
• all children 6 to 59 months of age
• all individuals who are pregnant or up to 2 weeks following delivery
• Indigenous peoples

If you are a person at high risk of flu-related complications and develop symptoms, contact a health care provider. If you need immediate medical attention, call 911 and tell them your symptoms.

The flu and common cold often present very similar, but the former can be more serious, and lead to complications like pneumonia (serious infection of the lungs). Visit the Ministry of Health’s Flu vs. common cold chart (external link) to help determine if you have a cold or the flu.

The flu and COVID-19 are caused by different viruses. They are both very contagious and have similar symptoms. This can make it hard to tell the difference between the flu and COVID-19 (external link) when symptoms appear. You can only confirm if you have the flu or COVID-19 with a test (e.g., a swab).

If you have symptoms of the flu and have not received a negative COVID-19 test, follow COVID-19 prevention measures (external link) to help keep others safe.

The flu is usually diagnosed by your health care provider through one or more of:

• symptoms
• laboratory tests (nasopharyngeal swab)

Most flu symptoms can be managed with:

• rest
• fluids, like water
• over the counter medications to reduce any fever or muscle aches

Speak to your family doctor, nurse practitioner or pharmacist about over-the-counter medications.

In some cases, a health care provider may prescribe specific antiviral medications, especially if you are:

• at high risk of flu-related complications
• very sick with severe symptoms

Contact your family doctor if flu symptoms persist or worsen, or call Health Connect Ontario (formerly TeleHealth) by calling 811 to speak with a nurse.

The flu shot is a vaccine designed to protect against strains of the flu virus that are expected to be circulating during the upcoming flu season. The vaccine stimulates your body’s immune system to fight off infection if you come into contact with the flu virus.

The flu shot is your best defense against the flu. The flu shot is recommended for almost everyone who is 6 months of age or older.

The flu shot protects you if you later get exposed to the virus by helping to:

• prevent you from getting very sick from flu-related complications;
• protect people close to you because, once vaccinated, you are less likely to spread the virus to others;
• reduce the overall burden on the health care system during respiratory virus season; and
• reduce your chances of being infected with the flu and other respiratory viruses at the same time, including COVID-19, which could lead to serious complications.

The flu shot will not protect you against other infections, such as COVID-19 or RSV, so it is also important to be up to date with recommended COVID-19 and RSV immunizations.

A new flu vaccine is produced every year to protect you, your family, and your loved ones during the upcoming flu season. It is important that you get a new flu shot every year because:

• Flu viruses can change over time; the annual shot includes the strains expected to circulate in the upcoming season based on close monitoring of viruses.
• The effectiveness of the flu shot can decrease over time, so receiving a flu vaccine each year helps to keep you protected.

Children from 6 months to less than 9 years of age who have never had a flu shot before should receive 2 doses. It is recommended that the interval between doses be at least 4 weeks apart during the current flu season.

The flu season typically runs from late fall to early spring. The flu shot takes approximately 2 weeks to take full effect. Get your flu shot as soon as the vaccine is available for you.

Talk to your health care provider or pharmacy to learn more.

Getting your flu shot is the most effective way to protect yourself and your loved ones against the flu and flu-related complications. If you get the flu, the flu shot may reduce the severity of the illness and the chances of developing flu-related complications.

The effectiveness of the vaccine can vary and may depend on:

• the health and age of the person getting the flu shot; and
• how well the vaccine matches with the circulating flu strains in that season

 The strains circulating in the population can sometimes change during the time it takes to produce a vaccine. When this happens, the flu shot may not work as well as expected.

 The flu shot protects against 3 or 4 different strains of the flu virus each season. The flu shot can still provide protection even when there is a less-than-ideal match between the vaccine and a circulating strain. This can result in lower effectiveness against one strain of the virus, but will still protect you.

Visit the Ministry of Health’s website on flu shot safety and effectiveness for more information (external link).

The influenza vaccine is safe. It is much safer to get the vaccine than influenza. Many people who receive the flu shot have no side effects. For those that do, side effects are usually mild and last a few days.

Visit the Ministry of Health’s website on flu shot safety and effectiveness for more information (external link).

The National Advisory Committee on Immunization (NACI) (external link) recommends that flu vaccine should be offered annually to anyone 6 months of age and older who does not have a contraindication to the vaccine. It is especially recommended for the following groups:

• People at high risk of flu-related complications or hospitalization
• Priority populations
• Individuals capable of transmitting influenza to those listed in the high-risk group above and/or to infants under 6 months of age
• People who provide essential community services

Visit the Ministry of Health’s Influenza website for more information on high-risk and priority populations (external link).

• Anyone who has had a serious allergic reaction (anaphylaxis) to a previous dose of influenza vaccine and/or to any ingredient in the vaccine, except for egg, should not be vaccinated. People with egg-allergies can safely receive any age-appropriate flu shot.
• Anyone who has developed Guillain-Barré Syndrome (GBS) within six weeks of a previous influenza vaccination should generally not be vaccinated, however this should be weighed against the risks of not being vaccinated against influenza.
• Anyone with a severe acute illness at the time of immunization should wait until the symptoms subside before being immunized. Immunization should not be delayed because of minor acute illness, with or without fever.
• Anyone less than 6 months of age.

Consult with your Health Care Provider to determine if the flu vaccine is right for you.

To get your free flu shot:

• visit a doctor or nurse practitioner
• visit a participating pharmacy*

*Children between the ages of 6 months and 2 years of age must visit a doctor or nurse practitioner. Looking for a family doctor? Visit our Halton Physicians Accepting New Patients webpage.

Find the closest participating pharmacy in:

• Burlington (external link)
• Halton Hills (external link)
• Milton (external link)
• Oakville (external link)

People 6 months of age or older can get their flu shot at the same time, or at any time before or after other vaccines, including the COVID-19 and respiratory syncytial virus (RSV) vaccines or RSV monoclonal antibody products. Speak to your health care provider if you have any questions.

All flu vaccine types are safe, effective and offer strong protection to seniors. Talk to your healthcare provider about which option is best for you. Do not delay vaccination to wait for a particular product.

Visit the Ministry of Health’s flu website for more information on flu shots available for those 65 and older (external link).

The information on this dashboard comes from several sources.

Data for current respiratory season:

All data for the current respiratory season is extracted on Wednesdays for data up to the end of the previous surveillance week.

• Percent Positivity: Capacity Planning and Analytics Division (CPAD), Respiratory Testing Report
• Outbreaks: Ontario’s Integrated Public Health Information System (iPHIS).
• Hospital bed occupancy: Ministry of Health, SAS Visual Analytics Tool, COVID Regional Hospital and Hospital Utilization reports.
• Emergency department visits: Acute Care Enhanced Surveillance (ACES) system.

Historical data:

• Percent Positivity (Sep 2021–Aug 2024): Ontario Agency for Health Protection and Promotion (Public Health Ontario). Ontario respiratory virus tool, extracted March 20, 2024.
• COVID-19 outbreaks (Sep 2021–Jun 2024): Public Health Case and Contact Management (CCM) system, extracted June 27, 2024.
• Other outbreaks (Sep 2021–Aug 2024): Integrated Public Health Information System (iPHIS), extracted July 16, 2025.

• The dashboard is updated every Thursday throughout the respiratory season. Data refreshes dynamically but is usually complete by 4 p.m., depending on server times.
• Data are grouped by respiratory seasons, which follow public health surveillance weeks:
  • Each season runs from September 1 to August 31 of the following year.
  • Surveillance weeks run Sunday to Saturday.
  • Typically, the week that includes September 1 marks the start of each season (week 35).
  • The current season (2025–26) runs from August 24, 2025, to August 29, 2026.
  • Dates align with the FluWatch Public Health Agency of Canada surveillance week schedule (external link).
• Numbers may differ from other reports because of different data sources, methods, or extraction/update times.
• Data are continuously updated as more information becomes available and are therefore subject to change with future dashboard updates.
  • iPHIS is regularly updated, so numbers reflect the most recent data at the time of extraction.
  • Counts may increase or decrease after data cleaning, updates or corrections.
• All data (except hospital bed occupancy) include Halton Region residents only.
  • Hospital bed occupancy reflects usage in the four hospitals within Halton Region, regardless of where patients live.

The Snapshot tab gives a quick overview of current respiratory virus activity among Halton residents.
It shows four indicators for COVID-19, influenza, and RSV (respiratory syncytial virus).

1. Overall activity (based on percent positivity)

2. Percent positivity (combined for influenza A and B)

3. Active outbreaks

4. Hospital bed occupancy

Each week’s data is compared to the previous week. Changes are shown as:

• ↑ Higher (orange arrow): Activity increased
• = Similar (grey equals sign): Little or no change
• ↓ Lower (blue arrow): Activity decreased

The criteria for each indicator are explained below.

 1. Overall Activity

• Higher (↑): Activity level increased to a higher category 
• Similar (=): No change in activity level
• Lower (↓): Activity level decreased to a lower category

 2. Percent Positivity

• Any move from 0% = Higher
• Any move to 0% = Lower

If percent positivity in the previous week was below 10%:

• Higher (↑): Increase of 0.5 percentage points or more
• Similar (=): Change of less than 0.5 percentage points
• Lower (↓): Decrease of 0.5 percentage points or more

If percent positivity in the previous week was 10% or more 

• Higher (↑): Increase of 5% or more

• Similar (=): Change of less than 5%
• Lower (↓): Decrease of 5% or more

 3. Active Outbreaks

• Any move from 0 = Higher
• Any move to 0 = Lower
• Higher (↑): an increase of 2 or more outbreaks
• Similar (=): Change of less than 2 outbreaks
• Lower (↓): a decrease of 2 or more outbreaks

 4. Hospital Bed Occupancy

• If the average count in the previous week was under 25 beds:
  • Higher (↑): Increase of 5 or more beds
  • Similar (=): Change of less than 5 beds
  • Lower (↓): Decrease of 5 or more beds
• If the average count in the previous week was 25 or more beds:
  • Higher (↑): Increase of 20% or more
  • Similar (=): Change of less than 20%
  • Lower (↓): Decrease of 20% or more

• Percent positivity is the percentage of tests that are positive in a given week. It’s calculated by dividing the number of positive tests in a 7-day surveillance week by the total number of tests performed during a 7-day surveillance week.
• Tests are assigned to a surveillance week based on the date the specimen was collected.
• Each test is counted separately, even if the same person was tested more than once in a week or over time.
• Trends over time should be interpreted carefully, since testing methods and eligibility have changed.
• When testing numbers are low, percent positivity can fluctuate more and may be less reliable.
• Lab data are assigned to a public health unit based on the patient’s postal code. If that information is missing, the submitter’s postal code is used instead. This may occasionally result in a test being assigned to the wrong health unit.

• Outbreaks are assigned to a surveillance week based on the date they were reported to Public Health.
• The criteria for declaring an outbreak can change over time. The dashboard shows outbreaks as they were entered in iPHIS or CCM, based on the criteria in place at the time.
• Only outbreaks in institutional settings are shown. These include hospitals, correctional facilities, long-term care homes, and retirement homes.
• The “Other” category includes outbreaks caused by entero/rhinovirus, parainfluenza, metapneumovirus, measles, or unspecified respiratory infections. These do not involve COVID-19, influenza, or RSV.
•  Some outbreaks involve more than one respiratory virus (called multi-organism outbreaks).
• The dashboard counts each outbreak once, unless it involves more than one of COVID-19, influenza, or RSV.  For example:
  1. COVID-19 and metapneumovirus → counted as one COVID-19 outbreak
  2. COVID-19, metapneumovirus, and influenza → counted as two outbreaks (COVID-19 and influenza)
  3. Metapneumovirus and parainfluenza → counted as one “Other” outbreak
• Active outbreaks (shown as a line) include any outbreaks that were still ongoing for at least one day during the surveillance week, no matter when they began.
• New outbreaks (shown as bars) are only counted once in the week they are reported, even if they continue afterward.
• Because it takes time to declare outbreaks over and update records in iPHIS, active outbreak counts may temporarily appear higher until all updates and documentation are complete.

• Bed occupancy data for influenza and RSV is only available starting from November 2022.
• The data shows the average daily number of patients occupying a bed in Halton hospitals who have COVID-19, influenza, or RSV during each surveillance week. Since the number of occupied beds can change daily, this is an average across the week.
• Beds in Halton hospitals may be occupied by patients from anywhere, not just Halton residents. Halton residents hospitalized outside Halton are not shown.
• Patients might be in the hospital because of complications from COVID-19, influenza, or RSV, or they might be hospitalized for other reasons but test positive for one of these infections.
• If a patient is infected with more than one of these viruses (COVID-19, influenza, RSV), their hospital bed is counted separately in each relevant category.

• Visits are counted in the surveillance week based on the date the person visited the emergency department.
• The data includes visits by Halton residents to any emergency department in Ontario.
• Visits are automatically grouped by the main symptoms reported (“chief complaint”). Because this is based on symptoms, some visits classified as respiratory or influenza-like illness might not actually be confirmed respiratory infections.
• The percentage of visits for respiratory or influenza-like illness is calculated by dividing the number of visits in these categories by the total number of emergency visits during the surveillance week.

• Differences between respiratory seasons happen for many reasons, such as:
  1. Which virus strains are circulating
  2. How well vaccines match those strains
  3. Which age groups are most affected
  4. How severe the illnesses are
  5. How many people get vaccinated
• Changes in who is eligible for testing affect the number and proportion of tests done for viruses like influenza, COVID-19, and RSV.
• Measures to control viruses (like COVID-19 restrictions) can also change virus activity. For example, COVID-19 restrictions also reduced flu and RSV activity.
• Because of these factors, comparing disease activity between seasons should be done with extreme caution. Differences in viral activity, testing rules, case definitions, and containment measures limit how comparable the data is over time and need to be considered when interpreting this data. 

Viral wastewater testing is no longer conducted in Halton. Data from wastewater testing at the remaining sites in Ontario (all located outside Halton) can be found in the Public Health Agency of Canada’s Wastewater monitoring dashboard (external link).