It’s flu season – here’s what you absolutely need to know

By Dr. Kelsey Bennett, VM-Med

It’s that time of year again. Everyone is talking about the flu. The flu and the flu vaccine are always one of the most common topics of conversation in my office during the fall and winter months. What is the flu? Is my illness the flu? Should I be vaccinated? Will the vaccine work? Here is some basic information about the flu that may help get you through the coming months.

What is the flu?

The flu, or influenza, is a virus that is passed from person to person during the colder months of the year. This is not limited to Canada or North America, but happens all around the world. There are several types of influenza virus, but humans are usually affected by influenza A and B. Sometimes, you will hear people using terms like H1N1 influenza as well. We sometimes describe particular kinds (strains) of influenza virus using this terminology, which actually describes two proteins that help make up the virus’ covering. These proteins can help scientists and doctors distinguish between different strains of the influenza virus. For instance, in 2009 there was a lot of talk in the media of Swine Flu. That particular flu virus was an influenza A virus, with the identifiers of H1N1.

How do you get the flu?

In short, it is very easy to contract the flu. When a person is sick with the flu (and for 1-2 days before they even start to feel sick), people ‘shed’ influenza virus in their respiratory tracts. Any saliva or mucus in an infected person can contain virus. When we cough, sneeze, or blow our noses, the virus is propelled into the air and on to the surfaces around us. Contact directly in the air, or on contaminated surfaces (including hands), can cause infection. This is what makes hand washing so important! It also means that when we are sick, we need to be vigilant in covering our mouths when we cough or sneeze (i.e. coughing or sneezing into your elbow/sleeve), and in washing our hands afterwards.

What are the symptoms of the flu?

Influenza viruses usually cause respiratory symptoms like cough, sore throat, and runny nose as well as muscle aches, fever, fatigue and headaches. Symptoms usually last between 7 to 10 days, and people usually recover on their own with time. Some people (the very young, the elderly, and people with any chronic illness or lung condition, in particular) are much more likely to become seriously ill because of the flu. In fact, Health Canada estimates that approximately 12,200 hospital admissions and 3,500 deaths occur annually in Canada due to the flu.

I will add a bit of a disclaimer here, that a lot of people catch a cold and believe that they’ve had the flu.  The common cold is not caused by influenza but is caused by other viruses like rhinovirus (about 50% of colds) and coronavirus (another 15% of colds). In fact, there are hundreds of viruses that can cause the common cold. They tend to cause symptoms that are more annoying than they are disabling. If you’ve experienced a few days to a week of runny nose, nasal congestion, cough and sore throat but you have NOT had symptoms like fever, muscle pains, and fatigue, then you’ve likely had a cold and not the flu. If on every day of your illness you were able to get out of bed (even if you didn’t want to and it took a lot more effort than usual) and head off to work or school, you likely had a cold and not the flu.

What about the flu vaccine?

This is probably the most common question that I am asked about flu. Should I get the flu vaccine and does it work? The short answers to those questions are probably, and sometimes. In fact, there is no perfect answer to either of those questions. Depending on which Canadian province you live in, our recommendations for who should be vaccinated change. In Quebec, our recommendations are to vaccinate specific groups of people who may be more vulnerable to the flu than others. In Ontario, it is now recommended that everyone be vaccinated. Typically, these recommendations don’t only reflect the people who are most likely to benefit from the vaccine, but also take into consideration that there may not be enough vaccine for everyone and we may have to prioritize the people who need it most.

The effectiveness of vaccines in protecting against the flu changes every year. So does the vaccine itself:  every year, the flu vaccine is redesigned to protect against particular strains of flu, usually 4 of them. Researchers make predictions several months before flu season as to which strains are most likely to be the most common, and we create a vaccine accordingly. Their predictions are not always correct, and this means that our vaccines are not always very effective. The effectiveness of the vaccine in preventing an infection amongst vaccinated individuals is usually about 30%. Unfortunately, this year we seem to have missed the mark by a larger margin and estimates are that effectiveness may be as low as 10%.  However, we should keep in mind that if we are vaccinated and do still get the flu, our illness may be less severe than it would have been otherwise.

I very frequently hear patients say that the flu vaccine gave them the flu, or that they are worried that the vaccine is not safe. The flu vaccine cannot give you the flu. The vaccine contains inactivated parts of the virus, which cannot cause infection. You may, however, feel a little bit down or sick after receiving a vaccine. This is because the vaccine activates your immune system, and an active immune system is part of what makes us feel sick when we are fighting any kind of infection. This immune response is your friend, as it means that your body is preparing itself to fight the flu if and when you are exposed to the real thing. Soreness and some skin irritation at the injection site are other common side effects.

Serious adverse reactions to the flu vaccine are very rare. The most common serious adverse reaction is an allergic reaction. In general, we take more care in vaccinating people who have allergies to eggs (although this is probably much less of a concern than we previously thought), and anyone who has had an allergic reaction to a vaccine in the past.

In general, choosing whether to receive a vaccine (or any medication) is a question of potential risks and benefits. What bad things may happen if you take this medication vs. what good things will come of taking it. In the case of the flu vaccine, the reality may be that while there is very little risk associated with flu vaccine, there may not be a huge benefit either. Having a discussion with your doctor or pharmacist is always a good idea, and may help you come to a more educated decision about receiving the flu vaccine.

The bottom line about the flu

I hope that this may have helped to clear up some flu-related questions and concerns. The bottom line is that flu season has arrived and is in full swing in Canada. We all need to be vigilant in washing our hands and taking whatever measures we can to protect ourselves, which may or may not include being vaccinated. If you are sick, do your best to stay home and to protect those around you by using a sleeve or tissue when you cough or sneeze, and vigilant hand washing. Happy flu season!

Dr. Bennett is the Family Doctor at VM-Med. VM-Med offers private family medicine services in downtown Montreal. If you are looking for a family physician, or need a complete physical (including ECG), need any kind of lab work (blood work) or imaging, VM-Med can help. With on-site imaging, and rapid access to blood lab exams, you’ll receive all your tests in one convenient visit.