I got the flu shot – why am I sick?

It’s that time of year again! We’ve been building towards it for the past couple months and doing our best to prepare our own family, and I know many of you have been doing the same. It’s cold and flu season and there’s a good chance that someone in your home is going to get sick. We’ve already had a bout of pneumonia and put in our time helping Thomas recover, keeping him out of preschool to prevent any chance of spreading it to someone else, and so far the rest of us have managed to avoid catching anything. But it’s early in the season, and we’re realistic. On average, kids will have six colds a year (!!!), and anyone with children who go to school is familiar with how quickly everything spreads from one kiddo to the rest of the class. It’s a rough go and we’re early in the season.

Through the holidays and especially in the last few days I’ve started to see more and more discussion of illness, both on social media and filling my inbox on various platforms. A lot of people are classifying their illness as the flu, some noting that they’d had their shot this year . But is that what it is?

Let’s have a quick recap of what true influenza symptoms look like, and compare them to the common cold.


Symptoms typically start 1-4 days after exposure. In healthy adults it usually lasts 2-10 days, and may last longer for children and the elderly, and for people with underlying health issues. Here are common flu symptoms:

  • fever
  • chills
  • cough
  • runny eyes
  • stuffy nose
  • sore throat
  • headache
  • muscle aches
  • extreme weakness and tiredness
  • vomiting and diarrhea sometimes occur, but are more common in children than adults


There are a lot of misconceptions about what the flu is, and the term is often applied to gastro illnesses. However, the flu is primarily a respiratory illness and the symptoms can be very similar to what you experience with a cold, though it can be much more serious. Here’s a quick comparison of the two, taken from the Government of Ontario’s fact page:


*The above information from this page is taken from the Government of Ontario’s site. If you have further questions, please speak with your doctor. Links to other government fact pages can be found on the resources page.


So, to the original question. I got the flu shot – why am I sick?

There are three things that may have happened.

1) It was most likely not influenza, but another bug. A lot of illnesses present with flu-like symptoms, but are something else. We can only know for sure through lab confirmation and that is typically only done in the most severe cases – usually when someone is admitted to hospital or through the autopsy process, but some doctors will test during a visit to the office or urgent care. When we received Jude’s results I questioned why flu testing isn’t done more routinely and was told that many illnesses present with flu-like symptoms, and unless the case is very severe the cause of the symptoms doesn’t change the treatment.

2) Second most likely, it was a strain that wasn’t covered by your flu shot. The shot is created with the strains that are most likely to affect the population based on global trends of flu activity each year. Children and seniors are recommended to receive the quadrivalent shot containing two A and two B strains, while most healthy low-risk adults receive the trivalent with two A and one B. A strains, like H1N1 and H3N2, are the strains that cause pandemics, while B strains are less prolific, but far more serious in young children and seniors, resulting in higher rates of mortality and hospitalization. You may have all contracted a strain that you weren’t immunized for, but there’s no way to know without lab confirmation if it was the flu.

3) Least likely but still a possibility, you may have failed to develop immunity. Jude is an example of this. He had his shot last December and contracted influenza B in May, and died hours after waking up with a low-grade fever. My other two also got pretty sick, but recovered fairly quickly. They were not tested for influenza at the time, but in light of Jude’s autopsy results we know it’s a strong possibility that they also got the flu. We can’t know for sure. We do know that even if you get a strain of influenza you’ve been immunized against, you are likely to experience far less severe symptoms than you would have had without the shot. As many as 90-96℅ of pediatric flu deaths are in children who were not vaccinated, for example. The flu shot is not a guarantee, unfortunately, just like any other vaccine. There will always be people in the community who failed to develop immunity after their vaccine, but because the vaccination rates for those illnesses are so much higher, they benefit from herd immunity. This isn’t the case with influenza. Only 1/3 Ontarians and only 20% of our children receive the vaccine and so when people – like Jude – who received their vaccine but fail to develop immunity come in contact with influenza, they’re just as vulnerable as they’d have been otherwise. This is why our personal choice about the flu shot has greater impact than just our own personal health. We affect all those around us when we decide whether or not to take part in public health, and we make a choice about whether or not we want to put those around us at greater risk.



If you get sick this season, whether with the flu or another communicable illness, here are steps you can take to help recover.

  • stay home to avoid spreading it to others in the community
  • get plenty of rest to allow your body to recover
  • drink plenty of fluids
  • avoid caffeine (it’s dehydrating)
  • treat pain and fevers with relievers such as acetaminophen or ibuprofen – do not give acetylsalicylic acid (Aspirin) to anyone under 18
  • treat muscle pain with hot baths and heating pads
  • gargle with salt water or use lozenges for sore throat
  • try saline spray for nasal congestion
  • avoid alcohol and tobacco

See a doctor if your symptoms get worse, or if you’re in a higher risk group.


  • babies and children under 5
  • adults over 65
  • pregnant women
  • people with underlying health issues
  • Aboriginal peoples


I can’t emphasize it enough. Whether you got the flu shot or not, if you get sick, if you have these symptoms, stay home. Just stay home. Don’t inflict this on people around you. I know it’s inconvenient and it can feel impossible to take the day off for illness – yours or your child’s – but the potential outcome of exposing others to your illness is devastating. Someone went to school sick in the spring and most of a kindergarten class got sick. Jude died. It might not look serious to you, but it can be deadly to someone else. Avoid contact with others until you’re at least 24 hours fever-free without medication. Treating a fever with Tylenol and sending to school is not acceptable.

I know it’s hard. But I can tell you from experience how much harder it is for someone you love to die from a preventable illness. Don’t let this be your family, and don’t let your family be the reason that someone else’s family loses someone.

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