It’s flu shot season and the mightiest will brag that they never get sick and others complain that despite getting the flu shot, they still got sick in the past.

If you get the flu shot, does that mean you won't get sick this winter?

If you got the flu shot in the past but still got sick, does that mean it didn’t work?

Let me be clear. The flu shot does not prevent you from getting the common cold. It helps prevent you from getting influenza, which is an entirely different virus. The confusion between the two is understandable since many of the symptoms overlap making it hard to tell which virus you have.

The common cold is caused by one of over 100 cold viruses whereas the influenza virus causes the flu. The common cold virus and the influenza virus are not the same thing.

The flu vaccine is for the influenza virus. So this winter, even if you get the flu shot, you may still the common cold, but you are much less likely to get a serious influenza infection.  Those with a serious influenza infection may need hospitalization especially if they are elderly, frail, or suffer from other medical conditions.

Each year, minor variations occur in both the common cold virus and the influenza virus preventing the development of a cure. Previous influenza viruses can be used to help design a vaccine, which tricks the body into thinking it was exposed to the influenza virus. This results in the body building antibodies that will be on hand to rapidly attack any exposure to the influenza virus, preventing the virus from establishing itself.

How can you differentiate between the flu and the common cold?

Influenza is very similar to the common cold in many ways, but the symptoms are much more intense and complications more severe with the influenza. Here is a table outlining some of the differences:

(you may need to turn your device sideways to see complete table)

Common Cold Influenza
Season All year around, but more common in the winter Fall to spring, peaking in winter
Onset and Duration Gradual onset of sore throat over 1-2 days followed by runny nose. Sneezing is more common. Better in 7-10 days with some symptoms lasting up to two weeks. Abrupt onset and can be severe. Possible sore throat. Symptoms last 1-2 weeks with some symptoms lasting longer
Chest Mild to moderate with hacking cough Cough and congestion can become quite severe
Fever Not always and if so usually less than 38.5 degrees. More common in children. Possibly severe especially in children, lasting several days. Shivering and chills in all ages.
Muscle aches and Fatigue Mild to moderate – still able to get through day. Can be extreme early on and can last several days to weeks
Headache Sometimes Common
Vomiting and Diarrhea Rare More common in children and elderly
Contagious For first few days. 2-4 From 1 day before symptoms up to 5-7 days after symptoms
Complications Sinus and middle ear infections possibly lasting a couple of weeks Sinusitis, bronchitis. Pneumonia which can be life threatening.


So what’s the big deal? Why protect ourselves against the influenza virus?

Symptoms from the flu virus can be severely debilitating even for healthy people. Getting the flu shot protects you and those around you by decreasing the spread of the virus. Young children, older adults, pregnant women and people with compromised immune systems are especially vulnerable and symptoms of the flu can hit them hard. Many people die each year from complications related to the flu.

Flu season has a huge impact on our already strained healthcare system. Most with the milder symptoms of the common cold won’t need to go to the hospital. Many with the flu will manage at home as well. In many others however, the symptoms of the flu will be very severe resulting in a surge of people visiting emergency departments for treatment. This surge of patients creates longer wait times in the emergency departments and occupy in-patient hospital beds to treat the flu. When hospitals are full, operations requiring an in hospital stay are at risk of being cancelled. Medical patients cannot be admitted to a ward bed and end up receiving care in the suboptimal conditions of overcrowded emergency departments and hallways. The effects of this are far reaching including added strain on the already burdened front line health care staff.

By getting the flu shot, each one of us can help reduce this risk. By getting the flu shot, not only will you and your loved ones stay healthier, but you will indirectly contribute to decreasing the burden on our emergency departments and healthcare system overall.

It is important to get the flu shot early as it takes your body up to two weeks to build antibodies to attack the influenza virus. Some may feel a low-grade fever or mild aches and pains lasting a day or two after getting the flu shot. Other prevention techniques are important to follow as well. Proper and frequent hand washing, coughing or sneezing into your elbow and saying home when you are sick will all help avoid transmission.

So remember, if you get the flu vaccine, chances are you are still might get the common cold this year, but your chances of getting the influenza are much less.

Dr. Rohit Kumar